Research & Scholarship

Current Research and Scholarly Interests

Clinical Trials

Perfusion CT as a Predictor of Treatment Response in Patients With Rectal CancerNot Recruiting

A research study of rectal cancer perfusion (how blood flows to the rectum over time). We
hope to learn whether perfusion characteristics of rectal masses may be predictive of
response to treatment and whether rectal perfusion characteristics can be used to follow
response to treatment.

Stanford is currently not accepting patients for this trial.For more information, please contact Laura Gable, 650-736-0798.

The purpose of this study is first, to determine whether baseline perfusion characteristics
of pancreatic cancer, as characterized by CT perfusion studies, can predict tumor response
to treatment by stereotactic body radiotherapy (SBRT). The second goal of this study is to
determine whether baseline perfusion characteristics in those patients with resectable
pancreatic cancer correlate with immunohistologic markers of angiogenesis such as
microvessel density and vascular endothelial growth factor (VEGF) expression.

Stanford is currently not accepting patients for this trial.For more information, please contact Lindee Burton, (650) 725 - 4712.

Publications

All Publications

Abstract

To evaluate the frequency of the "bright band sign" in patients with splenic infarcts as well as control patients and to thereby assess whether the bright band sign has potential utility as a sonographic sign of splenic infarction.Using an electronic search engine and image review, 37 patients were retrospectively identified with noncystic parenchymal splenic infarcts on sonography. Nineteen abnormal control patients with noninfarcted splenic lesions on sonography and 100 normal control patients with sonographically normal spleens were also identified. The sonographic appearance of each splenic lesion was evaluated by 2 reviewers and assessed for the bright band sign, defined as thin specular reflectors perpendicular to the sound beam within hypoechoic parenchymal lesions, and for the presence or absence of the classic sonographic appearance of splenic infarction. Possible histologic counterparts of the bright band sign were assessed in archival infarct specimens.The bright band sign was present in 34 (91.9%; 95% confidence interval [CI], 78.1%-98.3%) of 37 patients with splenic infarcts on sonography, including 12 (85.7%; 95% CI, 57.2%-98.2%) of 14 with classic and 22 (95.7%; 95% CI, 78.1%-99.9%) of 23 with nonclassic infarct appearances. No normal or abnormal control patients had the bright band sign. Histologic sections suggested that preserved splenic trabeculae within infarcts may generate the bright band sign.The bright band sign is a potentially useful sonographic sign of splenic infarction, which may confer additional sensitivity and specificity and may be particularly helpful with infarcts having nonclassic appearances.

Abstract

The sonographic identification of the normal appendix is crucial to the success of ultrasound as an effective screening method for diagnosing acute appendicitis. The normal appendix can be challenging to identify on sonography, however, because it is a narrow tubular structure and has variable sonographic appearances. Moreover, the tip of the appendix can be quite variable in location. In this article, we review the various sonographic appearances of the normal appendix and highlight strategies to improve its visualization.

Abstract

The success of minimally invasive surgery for hyperparathyroidism depends on accurate preoperative localization of the hyperfunctioning adenoma with imaging. Ultrasound is an excellent initial modality because it has a high positive predictive value, sensitivity, and specificity, while being inexpensive and noninvasive without use of ionizing radiation. Determining the exact location and number of adenomas is essential, because these factors guide the surgical approach. The goal of this review article was to discuss specific sonographic techniques that can be applied to find even the elusive adenoma, which include (1) compression scanning, (2) color Doppler, (3) scanning regions where ectopic glands may be located, and (4) evaluating intrathyroidal adenomas.

Abstract

Head and neck malignancies, including squamous cell carcinoma, lymphoma, and thyroid cancer, are a major cause of morbidity and mortality worldwide and frequently present with cervical lymphadenopathy. Distinguishing normal from malignant lymph nodes is critical for accurate staging, prognosis, and determination of optimal therapeutic options. Gray-scale, power, and color Doppler ultrasonography offers an inexpensive yet effective method in identifying abnormal cervical lymph nodes. Sonographic nodal features that should be assessed include size, shape, echotexture (including microcalcifications and cystic changes), presence of an echogenic hilus, and vascularity. Although no single sonographic feature can accurately distinguish malignant from normal nodes, a combination of these characteristics can help to make this determination.

Abstract

Sonography is the modality of choice for imaging cervical lymph nodes in patients with papillary thyroid cancer, both before surgery and for postoperative surveillance. Sonography is also an invaluable tool to guide fine-needle aspiration of abnormal nodes. Microcalcifications, cystic changes, abnormal morphology, and disordered vascularity are features of metastatic nodal involvement with papillary thyroid carcinoma and should be sought during surveillance scans as well as in targeting for fine-needle aspiration.

Abstract

Extrapancreatic perineural spread in pancreatic adenocarcinoma contributes to poor outcomes, as it is known to be a major contributor to positive surgical margins and disease recurrence. However, current staging classifications have not yet taken extrapancreatic perineural spread into account. Four pathways of extrapancreatic perineural spread have been described that conveniently follow small defined arterial pathways. Small field of view three-dimensional (3D) volume-rendered multidetector computed tomography (MDCT) images allow visualization of small peripancreatic vessels and thus perineural invasion that may be associated with them. One such vessel, the posterior inferior pancreaticoduodenal artery (PIPDA), serves as a surrogate for extrapancreatic perineural spread by pancreatic adenocarcinoma arising in the uncinate process. This pictorial review presents the normal and variant anatomy of the PIPDA with 3D volume-rendered MDCT imaging, and emphasizes its role as a vascular landmark for the diagnosis of extrapancreatic perineural invasion from uncinate adenocarcinomas. Familiarity with the anatomy of PIPDA will allow accurate detection of extrapancreatic perineural spread by pancreatic adenocarcinoma involving the uncinate process, and may potentially have important staging implications as neoadjuvant therapy improves.

Abstract

Studies to identify preoperative prognostic variables for pancreatic neuroendocrine tumor (PNET) have been inconclusive. Specifically, the prevalence and prognostic significance of radiographic calcifications in these tumors remains unclear.From 1998 to 2009, a total of 110 patients with well-differentiated PNET underwent surgical resection at our institution. Synchronous liver metastases present in 31 patients (28%) were addressed surgically with curative intent. Patients with high-grade PNET were excluded. The presence of calcifications in the primary tumor on preoperative computed tomography was recorded and correlated with clinicopathologic variables and overall survival.Calcifications were present in 16% of patients and were more common in gastrinomas and glucagonomas (50%), but never encountered in insulinomas. Calcified tumors were larger (median size 4.5 vs. 2.3 cm, P=0.04) and more commonly associated with lymph node metastasis (75 vs. 35%, P=0.01), synchronous liver metastasis (62 vs. 21%, P<0.01), and intermediate tumor grade (80 vs. 31%, P<0.01). On multivariate analysis of factors available preoperatively, calcifications (P=0.01) and size (P<0.01) remained independent predictors of lymph node metastasis. Overall survival after resection was significantly worse in the presence of synchronous liver metastasis (5-year, 64 vs. 86%, P=0.04), but not in the presence of radiographic calcifications.Calcifications on preoperative computed tomography correlate with intermediate grade and lymph node metastasis in well-differentiated PNET. This information is available preoperatively and supports the routine dissection of regional lymph nodes through formal pancreatectomy rather than enucleation in calcified PNET.

Adenocarcinoma of the uncinate process of the pancreas: MDCT patterns of local invasion and clinical features at presentationEUROPEAN RADIOLOGYPadilla-Thornton, A. E., Willmann, J. K., Jeffrey, R. B.2012; 22 (5): 1067-1074

Abstract

To compare the multidetector CT (MDCT) patterns of local invasion and clinical findings at presentation in patients with adenocarcinoma of the uncinate process of the pancreas to patients with adenocarcinomas in the non-uncinate head of the pancreas.We evaluated the two cohorts for common duct and pancreatic duct dilatation, mesenteric vascular encasement, root of mesentery invasion, perineural invasion and duodenal invasion. In addition, we compared the clinical findings at presentation in both groups.Common duct (P?0.001) and pancreatic duct dilatation (P?=?0.001) were significantly less common in uncinate process adenocarcinomas than in the non-uncinate head of the pancreas. Clinical findings of jaundice (P?=?0.01) and pruritis (P?=?0.004) were significantly more common in patients with lesions in the non-uncinate head of the pancreas. Superior mesenteric artery encasement (P?=?0.02) and perineural invasion (P?=?0.001) were significantly more common with uncinate process adenocarcinomas.Owing to its unique anatomic location, adenocarcinomas within the uncinate process of the pancreas have significantly different patterns of both local invasion and clinical presentation compared to patients with carcinomas in the non-uncinate head of the pancreas. Key Points • SMA encasement and perineural invasion were more common with uncinate process adenocarcinomas. • Common bile duct and pancreatic duct dilatation were less common in uncinate process adenocarcinomas • Jaundice and pruritis were more common with lesions elsewhere in the pancreatic head.

Abstract

The purpose of this study was to review the CT findings and clinical outcome in patients with incidentally discovered solid pancreatic masses.Over an 8-year period, from 2001 to 2009, we identified 24 patients with solid pancreatic masses incidentally detected by CT. There were 13 females and 11 males, with a mean age of 67 years. We determined the indication for initial CT, analyzed the CT features, and ascertained the clinical follow-up in all the patients.All of the solid masses were malignant. There were 14 adenocarcinomas and 10 neuroendocrine tumors. The most common indications for the initial CT were surveillance of an extrapancreatic malignancy (n = 10) and evaluation for hematuria (n = 6). On the initial CT, 16 of the patients (67%) had a clearly visible pancreatic mass. In eight patients isoattenuating masses were identified, only recognized by subtle signs including unexplained dilatation of the pancreatic duct (n = 5) or minimal contour deformity or density of the pancreas (n = 3). The mean survival time for the patients with adenocarcinoma was 21.6 months, and 42 months for the patients with neuroendocrine tumors.Although uncommon, incidentally discovered solid pancreatic masses are malignant neoplasms, either ductal adenocarcinomas or neuroendocrine tumors. Unlike incidentally discovered small cystic lesions, solid pancreatic lesions are often biologically aggressive.

Abstract

To assess early treatment effects on computed tomography (CT) perfusion parameters after antiangiogenic and radiation therapy in subcutaneously implanted, human colon cancer xenografts in mice and to correlate in vivo CT perfusion parameters with ex vivo assays of tumor vascularity and hypoxia.Dynamic contrast-enhanced CT (perfusion CT, 129 mAs, 80 kV, 12 slices × 2.4 mm; 150 ?L iodinated contrast agent injected at a rate of 1 mL/min intravenously) was performed in 100 subcutaneous human colon cancer xenografts on baseline day 0. Mice in group 1 (n=32) received a single dose of the antiangiogenic agent bevacizumab (10 mg/kg body weight), mice in group 2 (n=32) underwent a single radiation treatment (12 Gy), and mice in group 3 (n=32) remained untreated. On days 1, 3, 5, and 7 after treatment, 8 mice from each group underwent a second CT perfusion scan, respectively, after which tumors were excised for ex vivo analysis. Four mice were killed after baseline scanning on day 0 for ex vivo analysis. Blood flow (BF), blood volume (BV), and flow extraction product were calculated using the left ventricle as an arterial input function. Correlation of in vivo CT perfusion parameters with ex vivo microvessel density and extent of tumor hypoxia were assessed by immunofluorescence. Reproducibility of CT perfusion parameter measurements was calculated in an additional 8 tumor-bearing mice scanned twice within 5 hours with the same CT perfusion imaging protocol.The intraclass correlation coefficients for BF, BV, and flow extraction product from repeated CT perfusion scans were 0.93 (95% confidence interval: 0.78, 0.97), 0.88 (0.66, 0.95), and 0.88 (0.56, 0.95), respectively. Changes in perfusion parameters and tumor volumes over time were different between treatments. After bevacizumab treatment, all 3 perfusion parameters significantly decreased from day 1 (P ? 0.006) and remained significantly decreased until day 7 (P ? 0.008); tumor volume increased significantly only on day 7 (P=0.04). After radiation treatment, all 3 perfusion parameters decreased significantly on day 1 (P < 0.001); BF and flow extraction product increased again on day 3 and 5, although without reaching statistically significant difference; and tumor volumes did not change significantly at all time points (P ? 0.3). In the control group, all 3 perfusion parameters did not change significantly, whereas tumor volume increased significantly at all the time points, compared with baseline (P ? 0.04). Ex vivo immunofluorescent staining showed good correlation between all 3 perfusion parameters and microvessel density (?=0.71, 0.66, and 0.69 for BF, BV, and flow extraction product, respectively; P < 0.001). There was a trend toward negative correlation between extent of hypoxia and all 3 perfusion parameters (?=-0.53, -0.47, and -0.40 for BF, BV, and flow extraction product, respectively; P ? 0.05).CT perfusion allows a reproducible, noninvasive assessment of tumor vascularity in human colon cancer xenografts in mice. After antiangiogenic and radiation therapy, BF, BV, and flow extraction product significantly decrease and change faster than the tumor volume.

Abstract

The aim of this study was to evaluate for agreement with respect to how radiologists report incidental findings encountered on CT.A multiple-choice survey was designed to query radiologists about how they handle 12 incidental findings on body CT, assuming the patient is a 45-year-old woman with no history of malignancy. Included were a 1-cm thyroid nodule, a 5-mm noncalcified lung nodule, coronary artery calcification, a 2-cm adrenal nodule, a 2-cm pancreatic cyst, a 1-cm enhancing liver lesion, a 2-cm high-density renal cyst, short-segment small bowel intussusception, a 1-cm splenic cyst, focal gallbladder wall calcification, and a 3-cm ovarian cyst in both a premenopausal woman and a postmenopausal woman. Choices ranged from "do not report" to advising interventional procedures tailored to the organ. Surveys were administered to body CT attending radiologists at 3 academic institutions.Twenty-seven radiologists completed the survey. The mean experience level was 15.7 years after training. Seventy percent or greater agreement on interpretation was identified for only 6 findings: recommend ultrasound for a 1-cm thyroid nodule, recommend ultrasound for a 3-cm cyst in postmenopausal woman, follow Fleischner Society recommendations for a 5-mm lung nodule, describe only coronary calcification, and describe as likely benign both short-segment small bowel intussusception and a 1-cm splenic cyst.Agreement is lacking, both across institutions and within departments, for the management of 6 commonly encountered incidental findings on body CT. Individual departments should develop internal guidelines to ensure consistent recommendations based on existing evidence.

Abstract

Hereditary diffuse gastric cancer (HDGC) is an autosomal dominant cancer syndrome. Up to 30% of families with HDGC have mutations in the E-cadherin gene, CDH1. The role of prophylactic versus therapeutic gastrectomy for HDGC was studied prospectively.Eighteen consecutive patients with CDH1 mutations and positive family history were studied prospectively, including 13 without and 5 with symptoms. Proportions were compared by Fisher's exact test, and survival by the Breslow modification of the Wilcoxon rank-sum test.Each patient underwent total gastrectomy (TG), and 17 (94%) were found to have signet ring cell adenocarcinoma. Twelve of 13 asymptomatic patients had T1, N0 cancer, and only 2/12 (16%) had it diagnosed preoperatively despite state-of-the-art screening methods. Each asymptomatic patient did well postoperatively, and no patient has recurred. For five symptomatic patients, each (100%) was found to have signet ring cell adenocarcinoma (P = 0.002 versus asymptomatic) by preoperative endoscopy; three (60%) had lymph node involvement and two (40%) had distant metastases at time of operation. Two-year survival was 100% for asymptomatic and 40% for symptomatic patients (P

Abstract

Acute cholecystitis is a common cause of abdominal pain in the Western world. Unless treated promptly, patients with acute cholecystitis may develop complications such as gangrenous, perforated, or emphysematous cholecystitis. Because of the increased morbidity and mortality of complicated cholecystitis, early diagnosis and treatment are essential for optimal patient care. Nevertheless, complicated cholecystitis may pose significant challenges with cross-sectional imaging, including sonography and computed tomography (CT). Interpreting radiologists should be familiar with the spectrum of sonographic findings seen with complicated cholecystitis and as well as understand the complementary role of CT. Worrisome imaging findings for complicated cholecystitis include intraluminal findings (sloughed mucosa, hemorrhage, abnormal gas), gallbladder wall abnormalities (striations, asymmetric wall thickening, abnormal gas, loss of sonoreflectivity and contrast enhancement), and pericholecystic changes (echogenic fat, pericholecystic fluid, abscess formation). Finally, diagnosis of complicated cholecystitis by sonography and CT can guide alternative treatments including minimally invasive percutaneous and endoscopic options.

Abstract

Appendicitis is one of the most common causes of the acute abdomen often requiring emergent surgery. Delayed diagnosis leads to the progression of uncomplicated appendicitis to complicated (gangrenous, perforated) appendicitis, often changing clinical management. Computed tomography and ultrasound are imaging modalities of choice to preoperatively diagnose appendicitis. Recent concerns of radiation exposure and cost have renewed interest in using ultrasound as an initial, diagnostic study. A sonographic pictorial and histopathologic review of the continuum of appendicitis is presented. A comprehensive sonographic examination of the appendix should investigate the size (maximal diameter), the echogenic submucosal layer integrity, the mural color Doppler signature, the presence of a fecalith, and the periappendiceal changes. Features of an uncomplicated appendicitis include size greater than 6 to 7 mm, hyperemia on color Doppler, mural thickening, and an intact echogenic submucosal layer. Gangrenous appendicitis is characterized by loss of the echogenic submucosal layer with absent color Doppler flow. Loculated pericecal fluid, prominent pericecal fat, and circumferential loss of the submucosal layer are suggestive of perforation. Sonographic staging can triage management of appendicitis by directing urgent laparoscopic appendectomy for uncomplicated appendicitis, open appendectomy for complicated appendicitis, and conservative management (antibiotics with percutaneous drainage) for perforated appendicitis with abscess formation.

Abstract

Foreign objects are not infrequently seen at computed tomography (CT) of the abdomen and pelvis and may pose a diagnostic challenge to the radiologist, who must recognize the object, characterize its nature and location, and determine its clinical significance. Most foreign objects are incidentally detected at CT, but they may mimic a wide range of pathologic conditions. Some foreign objects (eg, an object that has been swallowed either intentionally or unintentionally) are the cause of the patient's signs and symptoms and require prompt medical attention. Other objects, such as a sponge or surgical instrument that has been retained postoperatively, may have medicolegal consequences. Furthermore, certain objects, such as intentionally concealed drug packets, may go undetected unless a high degree of suspicion exists and appropriate window settings are used to review the study. The radiologist should be familiar with the wide range of foreign objects that may be encountered at abdominopelvic CT, be able to recognize them promptly, and understand their implications for patient treatment.

Abstract

The purpose of this article is to characterize sonographic features of differentiated thyroid cancer recurrence in the thyroidectomy bed.Patients referred for biopsy of thyroidectomy bed lesions between February 2006 and December 2009 were identified. Patient data and gray-scale and color Doppler features were recorded.Results of ultrasound-guided biopsies of 30 nodules in 27 patients were reviewed. Twenty-five lesions yielded diagnostic findings, including 22 recurrences in 19 patients and three benign lesions in three patients. Five biopsies were nondiagnostic. Among the 22 recurrences, 21 (95%) were hypoechoic and one (5%) was mixed hypoechoic and hyperechoic on gray-scale imaging. On Doppler imaging, 100% of recurrences had detectable vascularity. Eight lesions (36%) had microcalcifications, and five (23%) had coarse calcifications; the average long-axis dimension was 1.5 cm. Of the five nondiagnostic lesions, four (80%) were hypoechoic, one (20%) was isoechoic, one (20%) had microcalcifications, none had coarse calcifications, and two (40%) had vascularity; the average long-axis dimension was 0.6 cm. Of the negative lesions, three (100%) were hypoechoic, two (66%) had vascularity, and two (66%) had coarse calcifications. No microcalcifications were seen, and the average long-axis dimension was 2 cm. Serum thyroglobulin (Tg) or anti-Tg antibodies were elevated in 12 (63%) of 19 patients with recurrence (eight [42%] with elevated Tg levels and four [21%] with elevated anti-Tg antibody levels).An ultrasound finding of a hypoechoic thyroidectomy bed lesion with internal vascularity and size greater than 6 mm is highly sensitive in predicting recurrence. Serum Tg levels were less sensitive than ultrasound in detection of recurrence in the thyroidectomy bed.

Abstract

There are numerous entities that can mimic acute appendicitis. Ultrasound and computed tomography are the most common first-line, cross-sectional imaging modalities in the acute care setting. Ideally, imaging will either confirm appendicitis or exclude it by identifying a normal appendix. In the latter scenario, an alternate diagnosis can frequently be established that range from genitourinary, gastrointestinal, to even abdominal wall processes. Imaging is especially helpful in cases of patients presenting with atypical signs/symptoms for acute appendicitis and those presenting with a classic presentation where an alternative diagnosis is determined. The correct diagnosis will allow the most appropriate clinical management and therapy; specifically, avoiding nonindicated surgery is essential. Common and uncommon mimics of acute appendicitis are discussed with specific attention to their sonographic and computed tomographic appearances.

Abstract

This article will review the current literature regarding the detection of thyroid nodules with an emphasis on CT diagnosis. We will also discuss management strategies.With advances in cross-sectional imaging, the detection of incidental thyroid nodules has increased significantly. Detection of thyroid nodules is common on chest CT that is being performed for unrelated reasons. The workup of these nodules can be timeconsuming and expensive.

Abstract

The bowel is a common site for pathologic processes, including malignancies and inflammatory disease. Colorectal cancer accounts for 10% of all new cancers and 9% of cancer deaths. A significant decrease in the incidence of colorectal cancer and cancer death rates has been attributed to screening measures, earlier detection, and improved therapies. Virtual colonoscopy (VC), also known as computed tomography colonography, is an effective method for detecting polyps. However, in light of increasing concerns about ionizing radiation exposure from medical imaging and potential increased risk of future radiation-induced malignancies, magnetic resonance imaging (MRI) is seen as an increasingly attractive alternative. Improvements in MRI technology now permit three-dimensional volumetric imaging of the entire colon in a single breath hold at high spatial resolution, making VC with MRI possible.

Abstract

The purpose of this article is to familiarize radiologists with the common pathways of extrapancreatic perineural invasion of pancreatic adenocarcinoma and to highlight the potential value of 3D volume-rendered MDCT in its diagnosis.The perineural plexuses closely follow peripancreatic vessels, which are well depicted by contrast-enhanced 3D volume-rendered imaging, thus facilitating the diagnosis of extrapancreatic perineural invasion of pancreatic adenocarcinoma.

Abstract

Ultrasonography is often the initial imaging study in patients who present with right upper quadrant abdominal complaints. However, due to its intrinsic technical limitations, ultrasonography generally has a lower sensitivity than contrast-enhanced computed tomography or magnetic resonance imaging in detecting hepatic lesions. In this review, we describe several subtle sonographic signs that suggest the presence of an otherwise inconspicuous focal liver lesion, including disease in the pleural space or the lung parenchyma, refractive edge shadows, distorted or absent venous landmarks, abnormal Doppler patterns, and venous thrombosis. When encountered, these features should trigger careful evaluation of the adjacent areas for abnormalities and may warrant further studies with computed tomography, magnetic resonance imaging, or positron emission tomography. We also summarize common sonographic findings of diffuse liver diseases, including fatty infiltration and cirrhosis.

Abstract

The objectives of our study were to describe a new CT sign of diaphragmatic injury, the "dangling diaphragm" sign, and assess its comparative utility relative to other signs in the diagnosis of diaphragmatic injury resulting from blunt trauma. CT scans of 16 blunt trauma patients (12 men and four women, mean age 36.6 years old) with surgically proven diaphragmatic injury and 32 blunt trauma patients (24 men and eight women; mean age 37.4 years old) without evidence of diaphragmatic injury at surgery were blindly reviewed by three board certified radiologists specializing in body imaging. Studies were evaluated for the presence of established signs of diaphragmatic injury, as well as the dangling diaphragm sign, in which the free edge of the torn hemidiaphragm curls inward from its normal course parallel to the body wall. The sensitivity and specificity of each sign were determined, as were the correlation between the signs and the interobserver agreement in evaluation of these findings. The radiologists' overall impression as to whether rupture was present was also recorded. In select cases, coronal and/or sagittal reformatted images were available, and they were reviewed following evaluation of the original axial images. Any change in interpretation due to these images was noted. The sensitivity of the radiologists' overall impression for detection of diaphragmatic injury was 77%, with 98% specificity. Individual signs of diaphragmatic injury had sensitivities ranging from 44% to 69%, with specificities of 98% to 100%. The dangling diaphragm sign had a sensitivity of 54% and a specificity of 98%, similar to the other signs. Multiple signs were present in most cases of diaphragmatic injury, and coronal and sagittal reformatted images had little impact. Diaphragmatic injury remains a challenging radiographic diagnosis. The dangling diaphragm is a conspicuous sign of diaphragmatic injury, and awareness of it may increase detection of diaphragmatic injury on CT studies.

Abstract

In this work, we demonstrate 3-D photoacoustic imaging of optically absorbing targets embedded as deep as 5 cm inside a highly scattering background medium using a 2-D capacitive micromachined ultrasonic transducer (CMUT) array with a center frequency of 5.5 MHz. 3-D volumetric images and 2-D maximum intensity projection images are presented to show the objects imaged at different depths. Due to the close proximity of the CMUT to the integrated frontend circuits, the CMUT array imaging system has a low noise floor. This makes the CMUT a promising technology for deep tissue photoacoustic imaging.

Abstract

The purpose of this series was to show the sonographic appearance of calcified cervical lymph nodes and the utility of sonographically guided fine-needle aspiration biopsy (FNAB) in the setting of metastatic squamous cell carcinoma (SCC).Two cases of confirmed metastatic SCC to cervical lymph nodes were identified. Sonography and sonographically guided FNAB were performed in both cases with positron emission tomography (PET)/computed tomography (CT) correlation.In case 1, sonography identified a diffusely calcified, avascular cervical lymph node. Positron emission tomography/CT suggested granulomatous disease as a cause for hypermetabolism; however, sonographically guided FNAB identified metastatic SCC. In the second case, FNAB initially performed without sonographic guidance did not show malignancy. Subsequent FNAB with sonographic guidance identified an abnormal cervical lymph node with focal calcifications and internal color Doppler flow. Metastatic SCC was diagnosed on histopathologic examination. Subsequent PET/CT confirmed multiple punctate calcifications in a hypermetabolic lymph node.Calcifications in cervical lymph nodes from metastatic SCC are very rare. These 2 cases show the variable sonographic appearances and the utility of sonographically guided FNAB in establishing the correct diagnosis.

Abstract

In this paper, we describe using a 2-D array of capacitive micromachined ultrasonic transducers (CMUTs) to perform 3-D photoacoustic and acoustic imaging. A tunable optical parametric oscillator laser system that generates nanosecond laser pulses was used to induce the photoacoustic signals. To demonstrate the feasibility of the system, 2 different phantoms were imaged. The first phantom consisted of alternating black and transparent fishing lines of 180 mum and 150 mum diameter, respectively. The second phantom comprised polyethylene tubes, embedded in chicken breast tissue, filled with liquids such as the dye indocyanine green, pig blood, and a mixture of the 2. The tubes were embedded at a depth of 0.8 cm inside the tissue and were at an overall distance of 1.8 cm from the CMUT array. Two-dimensional cross-sectional slices and 3-D volume rendered images of pulse-echo data as well as photoacoustic data are presented. The profile and beamwidths of the fishing line are analyzed and compared with a numerical simulation carried out using the Field II ultrasound simulation software. We investigated using a large aperture (64 x 64 element array) to perform photoacoustic and acoustic imaging by mechanically scanning a smaller CMUT array (16 x 16 elements). Two-dimensional transducer arrays overcome many of the limitations of a mechanically scanned system and enable volumetric imaging. Advantages of CMUT technology for photoacoustic imaging include the ease of integration with electronics, ability to fabricate large, fully populated 2-D arrays with arbitrary geometries, wide-bandwidth arrays and high-frequency arrays. A CMUT based photoacoustic system is proposed as a viable alternative to a piezoelectric transducer based photoacoustic systems.

Abstract

The purpose of this article is to show the value of volumetric oblique coronal reformation of CT data sets for assessing the normal anatomy and abnormalities of the ampulla of Vater.Volumetric oblique coronal reformations are a useful noninvasive method to provide diagnostic information about periampullary abnormalities as well as show secondary features important for local staging and management. The technique is also valuable in providing a time-efficient method to review pertinent findings with clinicians.

Abstract

Uterine perforation is an uncommon complication of intrauterine devices (IUDs). Perforating IUDs can migrate to various locations but paradoxically are rarely found in ovaries or broad ligament. We describe an unusual case of a 23-year-old woman 1-month postpartum with an IUD translocation to the right adnexa. The IUD was inserted only 1 week prior to presentation, and she experienced pain on insertion. After visualization by ultrasound, the IUD was laparoscopically removed. We suggest early use of ultrasound in cases of potential IUD migration, particularly in high-risk patients and when IUD insertion causes pain.

Abstract

Appendicitis is the most common surgical cause of acute abdominal pain in the pediatric population. Several conditions can mimic the clinical presentation of appendicitis, leaving imaging as an essential modality to uncover the etiology, yet under certain circumstances, it can be misleading. Here, we present three cases where findings on multidetector computerized tomography scans supported the diagnosis of appendicitis, yet an alternate cause was found. These cases highlight a particular pitfall of satisfaction of search.

Abstract

Advancements in both CT scanner technology and three-dimensional (3D) imaging software have now made it feasible to image patients with acute GI bleeding in an effort to identify the bleeding source. This pictorial essay will explore the potential role of utilizing 64 MDCT and 3D imaging in patients presenting with acute gastrointestinal bleeding. A discussion of current technology, appropriate CT protocols, and interpretation strategies will be included.

Abstract

The purpose of this study was to characterize color Doppler imaging features of retained products of conception (RPOC) with gray scale correlation.Clinically suspected cases of RPOC between January 2005 and February 2008 were reviewed. Patient data and relevant color Doppler and gray scale features were recorded.A total of 269 patients referred for sonographic evaluation for RPOC were identified. Thirty-five patients had confirmed pathologic diagnoses, 28 of whom had RPOC. In those with RPOC, 5 (18%) were avascular (type 0); 6 (21%) had minimal vascularity (type 1); 12 (43%) had moderate vascularity (type 2); and 5 (18%) had marked vascularity (type 3). Peak systolic velocities ranged from 10 to 108 cm/s (average, 36.1 cm/s). Resistive indices in arterial waveforms ranged from 0.33 to 0.7 (average, 0.5). Five (45%) of the patients with type 0 vascularity had RPOC; 6 (86%) of those with type 1 had RPOC; and 17 (100%) of those with types 2 and 3 had RPOC. An echogenic mass had a moderate positive predictive value (80%) but low sensitivity (29%) for RPOC.Color Doppler evaluation of the endometrium is helpful in determining the presence of RPOC. Endometrial vascularity is highly correlated with RPOC, whereas the lack of vascularity can be seen in both intrauterine clots and avascular RPOC.

Abstract

Hepatic infections include pyogenic and amebic abscesses and fungal and parasitic diseases. Entry of the infectious organisms into the liver can occur by hematogenous spread via the portal vein or hepatic artery, ascension of the infection from the biliary tract, or from trauma. Worldwide, liver abscess is most often caused by Entamoeba histolytica, but in the developed world, pyogenic liver abscess is more common. Fungal infection is most often seen in immunosuppressed chemotherapy patients, whereas parasitic infections are seen in patients with recent travel to endemic areas of Asia, Africa, and South America. Imaging, and in particular ultrasound, plays a crucial role in following patients from treatment to resolution of disease.We review the ultrasound and computed tomographic findings and the clinical features that are characteristic of hepatic pyogenic abscess, amebic abscess, fungal infection, and parasitic infection.

Abstract

Hereditary diffuse gastric cancer is a rare autosomal dominant cancer susceptibility syndrome caused by germline E-cadherin (CDH1) mutations in 40% of cases with a high degree of penetrance. Screening endoscopy has not been useful in identifying early cancer, in part owing to conflicting data concerning site(s) of involvement in the stomach and the lack of endoscopically detectable pathology. Risk-reducing total gastrectomy specimens from 8 asymptomatic adults with germline mutations in the CDH1 gene (3 different pedigrees) were studied using a sequential serial sectioning protocol with submission of the entire stomach for histologic analysis. The presence, size, and distribution of signet ring cell clusters were determined for each section and geographic maps of the invasive foci were constructed and compared with gastrectomy specimens from patients with germline E-cadherin mutation and symptomatic gastric cancer. All but 1 of the asymptomatic patients with germline mutations in the CDH1 gene had negative endoscopic screening. All risk-reducing gastrectomy specimens were macroscopically normal. All contained multiple foci (mean, 10.9) of microscopic intramucosal signet ring cell carcinoma confined to the superficial gastric mucosa; no invasion of submucosa was identified. In situ carcinoma was present in 6/8 cases. The majority of signet ring foci were located in the proximal one third of the stomach, most within oxyntic-type mucosa. The number and size of foci were not related to age, but there was a trend toward more severe disease burden in women. Stomachs from the symptomatic group of patients with germline CDH1 mutations exhibited infiltrative foci with higher Ki-67 labeling that extended well beyond the superficial mucosa. In addition, while superficial signet ring cancer exhibited decreased or absent E-cadherin and beta-catenin protein expression in all cases studied, deeply invasive signet ring cancer showed reversion to E-cadherin and beta-catenin protein expression in a subset of mutation carriers. Our study indicates that superficial intramucosal signet ring carcinoma, although widespread, is predominantly located in the proximal one third of the stomach in patients with E-cadherin gene mutations. The observed site predilection suggests a possible role for geographically targeted endoscopic surveillance biopsy in patients who elect to delay surgical intervention.

Abstract

The National Cancer Institute (NCI) sponsored the NCI Thyroid fine-needle aspiration (FNA) State of the Science Conference on October 22-23, 2007 in Bethesda, MD. The 2-day meeting was accompanied by a permanent informational website and several on-line discussion periods between May 1 and December 15, 2007 (http://thyroidfna.cancer.gov). This document summarizes matters addressing manual and ultrasound guided FNA technique and related issues. Specific topics covered include details regarding aspiration needles, devices, and methods, including the use of core needle biopsy; the pros and cons of anesthesia; the influence of thyroid lesion location, size, and characteristics on technique; the role of ultrasound in the FNA of a palpable thyroid nodule; the advantages and disadvantages of various specialists performing a biopsy; the optimal number of passes and tissue preparation methods; sample adequacy criteria for solid and cystic nodules, and management of adverse reactions from the procedure. (http://thyroidfna.cancer.gov/pages/info/agenda/)

Abstract

The purpose of this pictorial essay is to showcase the use of minimum intensity projection in the imaging of low attenuation structures such as the pancreatic duct.Minimum intensity projection is a valuable adjunct to other processing techniques for the diagnosis and staging of pancreatic adenocarcinoma and cystic tumors of the pancreas.

Abstract

Molecular imaging of the body involves new techniques to image cellular biochemical processes, which results in studies with high sensitivity, specificity, and signal-to-background. The most prevalently used molecular imaging technique in body imaging is currently fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET). FDG PET has become the method of choice for the staging and restaging of many of the most common cancers, including lymphoma, lung cancer, breast cancer, and colorectal cancer. FDG PET has also become extremely valuable in monitoring the response to therapeutic drugs in many cancers. New PET agents, such as fluorothymidine and acetate, have also shown promise in the evaluation of response to therapy and in the staging of prostate cancer. Magnetic resonance (MR) spectroscopy has shown promise in the evaluation of prostate cancer. Breast cancer evaluation benefits from advances in spectroscopic imaging and contrast-enhanced kinetic evaluation of vascular permeability, which is altered in neoplastic processes because of release of angiogenic factors. Superparamagnetic iron oxide (SPIO) particles represent the first of an expanding line of MR contrast agents that target specific cellular processes. SPIO particles have also been used in the evaluation of the cirrhotic liver and at MR lymphangiography.

Abstract

Approximately 1% to 3% of all gastric cancers are associated with families exhibiting an autosomal dominant pattern of susceptibility. E-cadherin (CDH1) truncating mutations have been shown to be present in approximately 30% of families with hereditary diffuse gastric cancer (HDGC) and are associated with a significantly increased risk of gastric cancer and lobular breast cancer.Individuals from a large kindred with HDGC who were identified to have a CDH1 mutation prospectively underwent comprehensive screening with stool occult blood testing, standard upper gastrointestinal endoscopy with random gastric biopsies, high-magnification endoscopy with random gastric biopsies, endoscopic ultrasonography, CT, and PET scans to evaluate the stomach for occult cancer. Subsequently, they each underwent total gastrectomy with D-2 node dissection and Roux-en-Y esophagojejunostomy. The stomach and resected lymph nodes were evaluated pathologically.Six patients were identified as CDH1 carriers from a single family. There were 2 men and 4 women. The mean age was 54 years (range, 51-57 years). No patient had any signs or symptoms of gastric cancer. Exhaustive preoperative stomach evaluation was normal in each case, and the stomach and adjacent lymph nodes appeared normal at surgery. However, each patient (6 of 6, 100%) was found to have multiple foci of T1 invasive diffuse gastric adenocarcinoma (pure signet-ring cell type). No patient had lymph node or distant metastases. Each was staged as T1N0M0. Each patient recovered uneventfully without morbidity or mortality.CDH1 mutations in individuals from families with HDGC are associated with gastric cancer in a highly penetrant fashion. CDH1 mutations are an indication for total gastrectomy in these patients. This mutation will identify patients with cancer before other detectable symptoms or signs of the disease.

Abstract

Ultrasonography is a useful imaging modality for assessing cervical lymphadenopathy in patients with head and neck carcinomas. Features of cervical lymph nodes using gray-scale and color and power Doppler ultrasonography can help to distinguish normal and reactive lymph nodes from potentially metastatic lymph nodes. The distinguishing features that separate abnormal from normal cervical lymph nodes include peripheral vascularity, shape, overall lymph node echogenicity, absence of hilus, presence of nodal microcalcifications, and cystic changes. Often, a combination of these features is needed to assign a cervical lymph node as being abnormal.

Abstract

Our purpose was to correlate the imaging findings of small cystic pancreatic lesions to the incidence of growth on follow-up imaging and their pathologic diagnoses.CT images for 159 patients with cystic pancreatic lesions were retrospectively evaluated and lesions were assessed for size, number, connection to the main pancreatic duct (MPD), MPD dilatation, and any presence of loculation, wall irregularity, thick septations, or solid components. A total of 86 patients had follow-up imaging with time periods of less than 6 months (n = 21), 6-12 months (n = 22), 1-2 years (n = 14), and greater than 2 years (n = 29). Lesion histology was available in 20 patients.Lesions with pathologic correlation proved to be: side branch intraductal papillary mucinous neoplasm or tumor (IPMT) (n = 5), combined type IPMT (n = 4), nonmucinous cyst (n = 4), chronic pancreatitis (n = 2), and reactive atypia with nonmucinous fluid (n = 1), combined type IMPT with foci of adenocarcinoma (n = 1), mucinous adenocarcinoma (n = 2), and nonmucinous adenocarcinoma (n = 1). Lesions with solid components were significantly more likely to grow and be malignant (P < 0.05). The presence of MPD dilatation was more common in patients with combined type IPMTs or malignancies. No other factors were predictive of malignancy.Solid components are predictive of malignancy, and MPD dilatation should prompt consideration of surgery. Other cystic lesions can be followed.

Abstract

In 80% to 90% of patients with primary hyperparathyroidism, a single parathyroid adenoma will be identified as the culprit, whereas the remaining 10% to 20% are caused by multiple adenomas, parathyroid hyperplasia, and rarely, parathyroid carcinoma. At the 2002 National Institute of Health consensus meeting, minimally invasive parathyroidectomy was endorsed as a promising and attractive alternative to total parathyroidectomy. Therefore, preoperative localization of the adenoma is critical in the clinical evaluation of the patient before surgical resection. Although adenomas less than 1 cm may be difficult to visualize sonographically, knowledge of typical imaging characteristics of parathyroid adenomas and use of special sonographic techniques will facilitate identification in most patients. Typical imaging characteristics of parathyroid adenomas include homogeneously hypoechoic echotexture on gray scale with an enlarged feeding artery and peripheral arc of vascularity seen on color and power Doppler. Proper neck extension, unilateral graded compression techniques, and patient swallowing will improve visualization of adenomas.

Abstract

The Society of Radiologists in Ultrasound convened a panel of specialists from a variety of medical disciplines to come to a consensus on the management of thyroid nodules identified with thyroid ultrasonography (US), with particular focus on which nodules should be subjected to US-guided fine needle aspiration and which thyroid nodules need not be subjected to fine-needle aspiration. The panel met in Washington, DC, October 26-27, 2004, and created this consensus statement. The recommendations in this consensus statement, which are based on analysis of the current literature and common practice strategies, are thought to represent a reasonable approach to thyroid nodular disease.

Abstract

To retrospectively determine if three-dimensional (3D) viewing improves radiologists' accuracy in classifying true-positive (TP) and false-positive (FP) polyp candidates identified with computer-aided detection (CAD) and to determine candidate polyp features that are associated with classification accuracy, with known polyps serving as the reference standard.Institutional review board approval and informed consent were obtained; this study was HIPAA compliant. Forty-seven computed tomographic (CT) colonography data sets were obtained in 26 men and 10 women (age range, 42-76 years). Four radiologists classified 705 polyp candidates (53 TP candidates, 652 FP candidates) identified with CAD; initially, only two-dimensional images were used, but these were later supplemented with 3D rendering. Another radiologist unblinded to colonoscopy findings characterized the features of each candidate, assessed colon distention and preparation, and defined the true nature of FP candidates. Receiver operating characteristic curves were used to compare readers' performance, and repeated-measures analysis of variance was used to test features that affect interpretation.Use of 3D viewing improved classification accuracy for three readers and increased the area under the receiver operating characteristic curve to 0.96-0.97 (P

Abstract

The Society of Radiologists in Ultrasound convened a panel of specialists from a variety of medical disciplines to come to a consensus on the management of thyroid nodules identified with thyroid ultrasonography (US), with particular focus on which nodules should be subjected to US-guided fine needle aspiration and which thyroid nodules need not be subjected to fine-needle aspiration. The panel met in Washington, DC, October 26-27, 2004, and created this consensus statement. The recommendations in this consensus statement, which are based on analysis of the current literature and common practice strategies, are thought to represent a reasonable approach to thyroid nodular disease.

Abstract

Papillary thyroid carcinoma (PTC) is the most common thyroid malignancy in children and adults, with an incidence of 22,000 cases per year in the United States. Differentiating PTC from more frequently occurring benign thyroid nodules has proved challenging as there may be significant overlap in their clinical presentation and sonographic appearance. That said, high-resolution ultrasound provides a safe and affordable way of identifying and characterizing thyroid nodules and guiding percutaneous biopsies. Although no single sonographic feature is pathognomonic for PTC, certain features should raise suspicion and the combination of several features may be even more suggestive. In this pictorial essay, we describe the high-resolution sonographic features of pathologically proven PTCs. The nodule number, echo texture, internal architecture, calcifications, margins, contours, vascularity, and lymph nodes are considered. While the classic sonographic description of PTC is a solitary, hypoechoic solid nodule with microcalcifications and intrinsic vascularity, in practice, PTC may manifest with a myriad of sonographic appearances making biopsy necessary for a definitive diagnosis.

Abstract

Computed tomography colonography (CTC) is a minimally invasive method that allows the evaluation of the colon wall from CT sections of the abdomen/pelvis. The primary goal of CTC is to detect colonic polyps, precursors to colorectal cancer. Because imperfect cleansing and distension can cause portions of the colon wall to be collapsed, covered with water, and/or covered with retained stool, patients are scanned in both prone and supine positions. We believe that both reading efficiency and computer aided detection (CAD) of CTC images can be improved by accurate registration of data from the supine and prone positions. We developed a two-stage approach that first registers the colonic central paths using a heuristic and automated algorithm and then matches polyps or polyp candidates (CAD hits) by a statistical approach. We evaluated the registration algorithm on 24 patient cases. After path registration, the mean misalignment distance between prone and supine identical anatomic landmarks was reduced from 47.08 to 12.66 mm, a 73% improvement. The polyp registration algorithm was specifically evaluated using eight patient cases for which radiologists identified polyps separately for both supine and prone data sets, and then manually registered corresponding pairs. The algorithm correctly matched 78% of these pairs without user input. The algorithm was also applied to the 30 highest-scoring CAD hits in the prone and supine scans and showed a success rate of 50% in automatically registering corresponding polyp pairs. Finally, we computed the average number of CAD hits that need to be manually compared in order to find the correct matches among the top 30 CAD hits. With polyp registration, the average number of comparisons was 1.78 per polyp, as opposed to 4.28 comparisons without polyp registration.

Abstract

The objective of this work was to develop and validate algorithms for detection and classification of hypodense hepatic lesions, specifically cysts, hemangiomas, and metastases from CT scans in the portal venous phase of enhancement. Fifty-six CT sections from 51 patients were used as representative of common hypodense liver lesions, including 22 simple cysts, 11 hemangiomas, 22 metastases, and 1 image containing both a cyst and a hemangioma. The detection algorithm uses intensity-based histogram methods to find central lesions, followed by liver contour refinement to identify peripheral lesions. The classification algorithm operates on the focal lesions identified during detection, and includes shape-based segmentation, edge pixel weighting, and lesion texture filtering. Support vector machines are then used to perform a pair-wise lesion classification. For the detection algorithm, 80% lesion sensitivity was achieved at approximately 0.3 false positives (FP) per slice for central lesions, and 0.5 FP per slice for peripheral lesions, giving a total of 0.8 FP per section. For 90% sensitivity, the total number of FP rises to about 2.2 per section. The pair-wise classification yielded good discrimination between cysts and metastases (at 95% sensitivity for detection of metastases, only about 5% of cysts are incorrectly classified as metastases), perfect discrimination between hemangiomas and cysts, and was least accurate in discriminating between hemangiomas and metastases (at 90% sensitivity for detection of hemangiomas, about 28% of metastases were incorrectly classified as hemangiomas). Initial implementations of our algorithms are promising for automating liver lesion detection and classification.

Abstract

To describe 2 cases of abdominal tuberculosis in which sonographic evaluation of mesenteric lymphadenopathy showed increased through-transmission suggestive of caseating necrosis.Two patients with abdominal pain and other symptoms (including fever, diarrhea, and weight loss) underwent abdominal sonography with a 6-MHz curved array transducer. One patient also underwent sonographically guided fine-needle aspiration of multiple lymph nodes, and the other underwent computed tomography, colonoscopy, and colon biopsy.In both patients, sonography showed multiple rounded hypoechoic lesions with increased ultrasound through-transmission suggestive of necrotic lymphadenopathy. No color flow was shown. In 1 case, the posterior acoustic enhancement was accentuated in the harmonic imaging mode. In the other case, the lesions shown on sonography corresponded to computed tomographic findings of low-density lymph nodes. Results of fine-needle aspiration and colon biopsy were positive for tuberculosis.Posterior acoustic enhancement in abdominal lymphadenopathy can suggest the diagnosis of tuberculous lymphadenitis. Detection of this finding is facilitated by scanning in the harmonic mode. Necrotic nodes will lack color flow and can be distinguished from lymphadenopathy of other causes. Sonography can also be used for fine-needle aspiration of necrotic nodes to yield a definitive diagnosis.

Abstract

We developed a novel computer-aided detection (CAD) algorithm called the surface normal overlap method that we applied to colonic polyp detection and lung nodule detection in helical computed tomography (CT) images. We demonstrate some of the theoretical aspects of this algorithm using a statistical shape model. The algorithm was then optimized on simulated CT data and evaluated using a per-lesion cross-validation on 8 CT colonography datasets and on 8 chest CT datasets. It is able to achieve 100% sensitivity for colonic polyps 10 mm and larger at 7.0 false positives (FPs)/dataset and 90% sensitivity for solid lung nodules 6 mm and larger at 5.6 FP/dataset.

Abstract

: To determine the feasibility of a computer-aided detection (CAD) algorithm as the "first reader" in computed tomography colonography (CTC).: In phase 1 of a 2-part blind trial, we measured the performance of 3 radiologists reading 41 CTC studies without CAD. In phase 2, readers interpreted the same cases using a CAD list of 30 potential polyps.: Unassisted readers detected, on average, 63% of polyps > or =10 mm in diameter. Using CAD, the sensitivity was 74% (not statistically different). Per-patient analysis showed a trend toward increased sensitivity for polyps > or =10 mm in diameter, from 73% to 90% with CAD (not significant) without decreasing specificity. Computer-aided detection significantly decreased interobserver variability (P = 0.017). Average time to detection of the first polyp decreased significantly with CAD, whereas total reading case reading time was unchanged.: Computer-aided detection as a first reader in CTC was associated with similar per-polyp and per-patient detection sensitivity to unassisted reading. Computer-aided detection decreased interobserver variability and reduced the time required to detect the first polyp.

Abstract

Uterine arteriovenous communications are uncommon lesions that may be associated with life-threatening postpartum and postinstrumentation hemorrhage.A primigravida presented with infected retained products of conception. Excessive hemorrhage of unclear etiology occurred at dilation and curettage. After a second episode of bleeding, the patient received a diagnosis of uterine arteriovenous fistula.Uterine arteriovenous communications should be included in the differential diagnosis in patients with excessive postpartum or postinstrumentation bleeding. Color and spectral flow Doppler can aid diagnosis and clinical management.

Abstract

Fat stranding adjacent to thickened bowel wall seen at computed tomography (CT) in patients with acute abdominal pain suggests an acute process of the gastrointestinal tract, but the differential diagnosis is wide. The authors observed "disproportionate" fat stranding (ie, stranding more severe than expected for the degree of bowel wall thickening present) and explored how this finding suggests a narrower differential diagnosis, one that is centered in the mesentery: diverticulitis, epiploic appendagitis, omental infarction, and appendicitis. The characteristic CT findings (in addition to fat stranding) of each of these entities often lead to a final diagnosis. Diverticulitis manifests with mild, smooth bowel wall thickening and no lymphadenopathy. Epiploic appendagitis manifests with central areas of high attenuation and a hyperattenuated rim, in addition to its characteristic location adjacent to the colon. In contrast, omental infarction is always centered in the omentum. The most specific finding of appendicitis is a dilated, fluid-filled appendix. Correct noninvasive diagnosis is important because treatment approaches for these conditions range from monitoring to surgery.

Abstract

To evaluate periaortic hematoma (PH) near the level of the diaphragm at abdominal computed tomography (CT) as an indirect sign of acute traumatic aortic injury after blunt trauma in patients with mediastinal hematoma.From 1998 to 2001, 97 patients with CT evidence of mediastinal hematoma after blunt thoracic trauma were retrospectively identified at two level 1 trauma centers. The presence or absence of PH near the level of the diaphragmatic crura was retrospectively established by a blinded reviewer at each institution. Aortic injury status was determined by reviewing angiographic, surgical, and clinical records. Sensitivity, specificity, positive and negative productive values, and positive and negative likelihood ratios were calculated.Among the 97 patients with mediastinal hematoma, 14 had both PH near the level of the diaphragm and aortic injury; six had aortic injuries without PH, five had PH near the level of the diaphragm without aortic injury, and 72 had no evidence of PH near the diaphragm and no aortic injury. Sensitivity for PH near the level of the diaphragm as a sign of aortic injury was 70%; specificity, 94%; positive predictive value, 74%; and negative predictive value, 92%. The positive likelihood ratio for the presence of aortic injury was 10.8, and the negative likelihood ratio was 0.3.PH near the level of the diaphragmatic crura is an insensitive but relatively specific sign for aortic injury after blunt trauma. The presence of this sign at abdominal CT should prompt imaging of the thoracic aorta to evaluate potential thoracic aortic injury.

Abstract

The objective of our study was to determine the negative predictive value of MDCT with curved planar reformations for detecting vascular invasion and predicting overall resectability in patients with pancreatic adenocarcinoma.Imaging findings related to vascular invasion and overall tumor resectability in 25 patients who underwent contrast-enhanced biphasic MDCT evaluation were correlated with actual vessel invasion and overall resectability determined at surgery and pathologic examination. The presence of vascular invasion was assessed in 110 major peripancreatic vessels in 22 patients who underwent resection.On MDCT, 23 (92%) of 25 patients were deemed to have resectable pancreatic adenocarcinoma. The tumors in the remaining two (8%) were considered not resectable because of the presence of vascular invasion (which was confirmed in only one patient at surgery). Of those 23 patients deemed to be candidates for curative resection on the basis of MDCT results, 20 were found to have resectable adenocarcinoma at time of surgery, yielding a negative predictive value for MDCT of 87% (20/23 patients) for overall resectability. In the other three patients, adenocarcinoma was deemed to be unresectable because of small metastases to the liver (two patients) or to the peritoneum (one patient) discovered at surgery. For detection of vascular invasion, MDCT yielded a negative predictive value of 100% (108/108 vessels) with no false-negative findings and an accuracy of 99% (109/110 vessels) with 108 true-negative findings, one true-positive finding, and one false-positive finding.Our preliminary data on MDCT show that the technique has excellent negative predictive value for vascular invasion and good negative predictive value for overall tumor resectability in patients with pancreatic adenocarcinoma, suggesting an improvement over previous results reported using single-detector CT. The problem of undetected micrometastases to the liver and peritoneum remains.

Abstract

To determine the relative frequency of various sonographic findings in papillary carcinoma of the thyroid.We retrospectively analyzed the sonographic features in 55 patients with proven papillary carcinoma of the thyroid. Sonographic features analyzed were echo texture, cystic change, margin, contour, presence of a peripheral halo, vascularity, and calcification pattern. Features were classified as common (> or = 35% of cases) or uncommon (< 10% of cases). Combinations of features were also analyzed.Common sonographic features of papillary carcinoma included hypoechoic texture (86%), microcalcifications (42%) or no calcifications (47%), well-defined margins (47%), and intrinsic hypervascularity (69%). Uncommon features included hyperechoic or mixed echo texture, cystic elements, irregular margins, hypovascularity, and coarse or peripheral calcifications. Of the 29 lesions that had calcifications, 20 (69%) had microcalcifications; 5 (17%) had coarse calcifications; and 1 had peripheral calcifications. In total, 54% of cases had at least 1 uncommon feature, and 11% had 2 or more uncommon features. Cystic carcinomas were rare and accounted for only 6% of lesions; all had hypervascular solid components. No carcinomas in our series were completely avascular.There is a broad spectrum of sonographic findings in papillary carcinoma of the thyroid. Half of the lesions in this series had at least 1 uncommon sonographic feature.

Abstract

Detection and staging of pancreatic malignancies remains a challenge for radiologists. Considering the poor prognosis of pancreatic adenocarcinoma, accurate preoperative staging is the key to a possibly curative surgical treatment. Contrast-enhanced helical CT has been the most commonly used for evaluation of pancreatic cancer in many institutions, although it suffers from many limitations. With the fast pace of advances in multidetector CT (MDCT), and the beginning clinical implementation of 16-row scanners, improvements in spatial resolution in the z-axis with near-isotropic imaging provide exquisite multiplanar reconstructions of pancreatic anatomy. This article provides an overview of current MDCT technique and protocols for assessment of pancreatic adenocarcinoma, and describes new 3D-display methods for effective visualization of large data sets provided by MDCT.

Abstract

Adrenal cysts are rare and are often found incidentally during abdominal imaging for another reason. We describe two cases of adrenal cysts, one of which was found to be a cystic pheochromocytoma. Most cystic pheochromocytomas are not diagnosed by urinary screening studies, and the first indication of a pheochromocytoma may be hemodynamic instability during resection. We review the literature on adrenal cysts and make recommendations for the management of cystic adrenal masses.

Abstract

The purpose of this study was to describe the technique of laparoscopic right radical nephrectomy incorporating intraoperative, real-time ultrasonography in the management of renal cell carcinoma with level 1 renal vein tumor thrombus. With the patient in a modified flank position, a transperitoneal four-port approach was used to laparoscopically resect an 8.5-cm right renal mass with tumor thrombus extending to, but not into, the inferior vena cava. Early arterial control with gentle traction on the right renal vein provided a short proximal renal venous segment devoid of tumor on laparoscopic inspection. Intraoperative laparoscopic ultrasonography allowed confident identification of the proximal extent of the tumor thrombus. After hilar control, complete resection and intact removal of the renal specimen was performed using standard non-hand-assisted laparoscopic techniques. The actual surgical time was 180 minutes. Surgical resection was successfully performed laparoscopically. No postoperative complications or hospital readmission occurred. Pathologic examination confirmed T3b renal cell carcinoma with negative surgical margins. Laparoscopic right radical nephrectomy incorporating intraoperative, real-time ultrasonography is feasible in the management of renal cell carcinoma with a large-sized level 1 renal vein thrombus. Additional studies are necessary to evaluate its role in urologic oncologic surgery.

Abstract

An important feature of multidetector-row helical computed tomography (CT) is the increased speed of scanning that permits routine use of very thin collimation and acquisition of near isometric imaging data of the abdomen within the time span of a single breath-hold. The parallel escalation in the capabilities of workstations makes feasible the practical use of advanced postprocessing techniques to create high quality volumetric imaging. This article highlights the unique contributions of multidetector-row CT and advanced postprocessing techniques to the evaluation of the pancreas and peripancreatic vascular structures and their value in the diagnosis and staging of pancreatic neoplasms.

Abstract

Colorectal cancer can easily be prevented provided that the precursors to tumors, small colonic polyps, are detected and removed. Currently, the only definitive examination of the colon is fiber-optic colonoscopy, which is invasive and expensive. Computed tomographic colonography (CTC) is potentially a less costly and less invasive alternative to FOC. It would be desirable to have computer-aided detection (CAD) algorithms to examine the large amount of data CTC provides. Most current CAD algorithms have high false positive rates at the required sensitivity levels. We developed and evaluated a postprocessing algorithm to decrease the false positive rate of such a CAD method without sacrificing sensitivity. Our method attempts to model the way a radiologist recognizes a polyp while scrolling a cross-sectional plane through three-dimensional computed tomography data by classification of the changes in the location of the edges in the two-dimensional plane. We performed a tenfold cross-validation study to assess its performance using sensitivity/specificity analysis on data from 48 patients. The mean specificity over all experiments increased from 0.19 (0.35) to 0.47 (0.56) for a sensitivity of 1.00 (0.95).

Abstract

To evaluate the utility of curved planar reformations compared with standard transverse images in the assessment of pancreatic tumors.Forty-three patients suspected of having pancreatic tumors underwent contrast material-enhanced biphasic multi-detector row computed tomography (CT). Curved planar reformations were generated along the pancreatic duct, common bile duct, and major mesenteric vessels. Three blinded independent readers assessed the curved planar reformations and transverse images separately for the presence of tumor, resectability, and vascular involvement. The results were compared with those of a consensus panel who evaluated the curved planar reformations and transverse images together along with clinical data and surgical findings.Of 43 patients, 20 had pancreatic malignancies as judged by the consensus panel and proven at biopsy and/or clinical follow-up. For tumor detection, transverse images and curved planar reformations had an average sensitivity of 95.0% and 98.4% (P >.05), respectively, and an average specificity of 90.9% and 91.3% (P >.05), respectively. For tumor resectability, transverse images and curved planar reformations had an average sensitivity of 85.7% and 71.4% (P >.05), respectively, and an average specificity of 85.2% and 84.3% (P >.05), respectively. Average interpretation time was 6.4 minutes with transverse images and 4.1 minutes with curved planar reformations.Curved planar reformations are equivalent to transverse images in the detection of pancreatic tumors and determination of surgical resectability.

Abstract

Surgical resection is the only curative treatment option for locoregional recurrence of well-differentiated thyroid cancer that does not trap radioiodine. We hypothesized that intraoperative ultrasonography would aid in the localization of recurrent thyroid cancer and would enhance the ability to perform a complete resection.Between June 2000 and October 2001, 13 patients with recurrent, scan-negative, papillary thyroid cancer were explored by using intraoperative ultrasonography.All patients had identification and resection of recurrent papillary thyroid cancer. Eleven patients had a complete resection, and 2 patients had incomplete resection as a result of local invasion. Ultrasound was required for identification of tumor in 7 patients and included all patients with a history of external beam radiotherapy. In 6 of these 7 patients, the tumor was paratracheal or invasive into the trachea or thyroid cartilage. In 11 patients with detectable serum thyroglobulin preoperatively, the level demonstrated a decline in 10 patients and became undetectable in 7 patients.Intraoperative ultrasonography is a useful method to identify nonpalpable, locoregional recurrences of thyroid cancer. Ultrasound was particularly helpful in patients who had previous external beam radiotherapy and in the identification of tumor nodules of 20 mm or less that were invasive or adherent to the airway.

Abstract

Gallbladder injuries after blunt abdominal trauma are rare and often follow a vague and insidious clinical course. Consequently, gallbladder injuries commonly go undiagnosed until exploratory laparotomy. Early diagnosis is essential, because trauma to the gallbladder is typically treated surgically, and delay in treatment can result in considerable mortality and morbidity. With sonography emerging as a first-line modality for evaluation of intra-abdominal trauma, sonographers may wish to become more familiar with the appearance of gallbladder injury on sonography to facilitate earlier diagnosis and to improve treatment and prognosis. We report a case of gallbladder perforation after blunt abdominal trauma diagnosed on the basis of computed tomography (CT) and sonography.

Abstract

To determine which patients suspected of having acute appendicitis benefit from preoperative imaging.The medical records of 462 consecutive patients who underwent appendectomy for clinically suspected acute appendicitis and underwent preoperative evaluation at our institution were retrospectively reviewed. Patients were divided into four groups: women (n = 166), girls (n = 46), men (n = 178), and boys (n = 72). Preoperative computed tomography (CT) or ultrasonography (US), requested by the referring clinician, was performed in 313 of the 462 patients. Unnecessary, or negative, appendectomy and perforation rates were calculated for each group for preoperative evaluation with CT, with US, and with neither CT nor US. In addition, the sensitivity and positive predictive value of CT and US were calculated for diagnosing appendicitis.In women, the negative appendectomy rate was significantly lower for those who underwent preoperative CT (7% [six of 85 patients], P =.005) or US (8% [four of 49 patients], P =.019), as compared with 28% [nine of 32 patients] for those who underwent no preoperative imaging (P >.35 for all groups). The negative appendectomy rates for girls, men, and boys were not significantly affected by preoperative imaging. The sensitivity of CT and US for diagnosing acute appendicitis exceeded 93% and 77%, respectively, in all groups. The positive predictive values for both CT and US were greater than 92% in all groups.Women suspected of having appendicitis benefit the most from preoperative CT or US, with a statistically significantly lower negative appendectomy rate than women who undergo no preoperative imaging. Therefore, we propose that preoperative imaging be considered part of the routine evaluation of women suspected of having acute appendicitis.

Abstract

Multidetector-row CT provides excellent visualization of the pancreas and peripancreatic structures, yielding information that is crucial for detecting pancreatic neoplasms and accurately determining their staging. This new technology enables the acquisition of large volumetric data sets to create high-quality curved planar reformations that clearly depict the common bile duct, the pancreatic duct, and the peripancreatic vasculature. Additionally, curved planar reformations highlight critical anatomic and pathologic relationships which are useful for surgical planning in patients with resectable disease.

Abstract

Diagnostic sonography is experiencing a breath-taking period of technological advancement. Ultrasound contrast agents, new imaging techniques, and handheld instruments will play a role in facilitating more diagnostic power in high-end imaging and insuring more widespread use of diagnostic sonography in medicine in general.

Abstract

To review the sonographic features and focused sonographic scanning techniques that may assist in the preoperative localization of parathyroid adenomas in patients with primary hyperparathyroidism.The sonographic findings were reviewed in 54 of 58 consecutive patients with pathologically proven parathyroid adenomas. A systematic scanning approach including real-time gray scale, color and power Doppler, and graded compression gray scale imaging was used in all patients.Fifty-four (93%) of 58 proven adenomas were correctly identified by sonography. Gray scale imaging alone was sufficient for identifying 26 (100%) of 26 large (> or =1-cm) and 3 (11%) of 25 small (<1-cm) parathyroid adenomas. However, for 25 (89%) of 28 small adenomas, a combination of color and power Doppler and graded compression real-time gray scale imaging was required for sonographic localization and identification.Knowledge of typical locations and characteristic imaging features, as well as a systematic scanning approach, can result in accurate preoperative sonographic localization of parathyroid adenomas.

Abstract

The authors developed and evaluated a method to automatically create interactive vascular curved planar reformations with computed tomographic (CT) angiographic data. The method decreased user interaction time by 86%, from 15 to 2 minutes. Expert reviewers were asked to indicate their confidence in differentiating automatically created images from clinical-quality manually produced images. The area under the receiver operating characteristic curve was 0.45 (95% CI: 0.39, 0.51), and a test of equivalency indicated that reviewers could not distinguish between images. They also graded image quality as equivalent to that with manual methods and found fewer artifacts on automatically created images. Automatic methods rapidly produce curved planar reformations of equivalent quality with reduced time and effort.

Abstract

Three bowel distention-measuring algorithms for use at computed tomographic (CT) colonography were developed, validated in phantoms, and applied to a human CT colonographic data set. The three algorithms are the cross-sectional area method, the moving spheres method, and the segmental volume method. Each algorithm effectively quantified distention, but accuracy varied between methods. Clinical feasibility was demonstrated. Depending on the desired spatial resolution and accuracy, each algorithm can quantitatively depict colonic diameter in CT colonography.

Abstract

Automatic analysis was performed of four-dimensional ultrasonographic (US) data in the carotid artery. The data, which were acquired in 31 subjects (eight healthy volunteers and 23 patients) by using a US scanner fitted with a special probe, were successfully processed. Acquisition time averaged 12 minutes. Data for all healthy volunteers (n = 8) and patients with complete occlusions (n = 3) were correctly classified. Data for two of the 12 patients with mild to severe (but not occlusive) disease were misclassified by one category.

Abstract

We evaluated the incidence and organ distribution of arterial extravasation identified using contrast-enhanced helical CT in patients who had sustained abdominal visceral injuries and pelvic fractures after blunt trauma.Five hundred sixty-five consecutive patients from four level I trauma centers who had CT scans showing abdominal visceral injuries or pelvic fractures were included in this series. The presence or absence of arterial extravasation, as well as the anatomic sites of arterial extravasation, was noted. We obtained clinical follow-up data, including surgical or angiographic findings.In our series, 104 (18.4%) of 565 patients had arterial extravasation. Of the 104 patients, 81 (77.9%) underwent surgery, embolization, or both. The combined rate of surgery or embolization in patients with arterial extravasation was statistically higher than expected at all four institutions (p <0.001). The spleen was the most common organ injured, occurring in 277 (49.0%) of 565 patients, and arterial extravasation occurred in 49 (17.7%) of 277 patients with splenic injury. Several other visceral injuries were associated with arterial extravasation, including hepatic, renal, adrenal, and mesenteric injuries.Based on the limited reports of arterial extravasation in the nonhelical CT literature, the percentage (18%) of clinically stable patients in our study with CT scans showing arterial extravasation was higher than anticipated. This finding likely reflects the improved diagnostic capability of helical CT. Although the spleen and liver were the organs most commonly associated with arterial extravasation, radiologists should be aware that arterial extravasation may be associated with several other visceral injuries.

Abstract

We examined the impact of the increased sensitivity for hypervascular masses of multidetector CT hepatic arteriography on treatment decisions involving selective chemoembolization of hepatocellular carcinomas.Thirty patients were referred for chemoembolization of unresectable hepatocellular carcinoma. Initial selective chemoembolization plans were formulated on the basis of diagnostic biphasic CT or MR imaging. Ultrafast CT hepatic arteriography was performed using a multidetector CT scanner and selective contrast material injection into the hepatic artery. The entire liver was scanned in a single breath-hold of approximately 20 sec with a slice thickness of 1 mm. Lesions and their arterial supplies were identified, and these data were immediately used to formulate a final plan for chemoembolization.Hypervascular masses were detected in 29 patients. In 16 (53%) of the patients, preprocedural CT or MR imaging underestimated the number of lesions. In nine (30%) of these 16 patients, the additional lesions were detected only on CT hepatic arteriography, not on conventional angiography. CT hepatic arteriography findings had a major impact on planning the way in which chemoembolization treatment was performed. In three of the nine patients, the previously undetected lesions were treated with additional superselective chemoembolization. In the other six patients, chemoembolization was performed less selectively than originally planned.Primarily because of the high sensitivity of multidetector CT hepatic arteriography in revealing small and multifocal hepatomas, findings of this modality frequently alter treatment plans involving selective administration of chemoembolic material.

Abstract

Adenomatous polyps in the colon are believed to be the precursor to colorectal carcinoma, the second leading cause of cancer deaths in United States. In this paper, we propose a new method for computer-aided detection of polyps in computed tomography (CT) colonography (virtual colonoscopy), a technique in which polyps are imaged along the wall of the air-inflated, cleansed colon with X-ray CT. Initial work with computer aided detection has shown high sensitivity, but at a cost of too many false positives. We present a statistical approach that uses support vector machines to distinguish the differentiating characteristics of polyps and healthy tissue, and uses this information for the classification of the new cases. One of the main contributions of the paper is the new three-dimensional pattern processing approach, called random orthogonal shape sections method, which combines the information from many random images to generate reliable signatures of shape. The input to the proposed system is a collection of volume data from candidate polyps obtained by a high-sensitivity, low-specificity system that we developed previously. The results of our ten-fold cross-validation experiments show that, on the average, the system increases the specificity from 0.19 (0.35) to 0.69 (0.74) at a sensitivity level of 1.0 (0.95).

Abstract

Since the advent of automated serum analysis, patients with primary hyperparathyroidism (PHPT) are often asymptomatic at presentation or have mild symptoms attributable to the disease. Parathyroid crisis is a rare and potentially fatal complication of PHPT in which patients develop severe hypercalcaemia with signs and symptoms of multiple organ dysfunction. A case of parathyroid crisis in a 20 year old man who presented with brown tumours and renal stones is described.

Abstract

In a prospective consecutive series, 53 revision hip arthroplasties were performed in 51 patients. Pre- and postoperative Duplex ultrasonography examinations were reviewed by an independent, experienced radiologist. Three of 51 patients (53 procedures) had evidence of chronic deep venous thrombosis (DVT) or other venous abnormality preoperatively, yielding an incidence of 5.6%. One (1.9%) patient developed an acute DVT postoperatively despite pharmacological and mechanical preventative measures. These results indicate the use of preoperative ultrasonography as a screening tool prior to revision hip arthroplasty is not warranted based on the low incidence of acute or chronic DVT detected preoperatively. Long-term anticoagulation, when necessary, can be based on the findings of a postoperative scan.

Abstract

A variety of high-resolution imaging techniques are currently available for the evaluation of patients with RUQ pain. In these patients, an imaging approach that is based on identifying the presence of certain clinical signs and symptoms can aid in choosing the appropriate imaging modality and establishing the diagnosis. For patients presenting with a positive Murphy sign, sonography and biliary scintigraphy are the most useful initial imaging techniques. In patients with fever and a negative Murphy sign, a combination of sonography and contrast-enhanced CT can establish the diagnosis in most cases. And finally, in patients without fever or a positive Murphy sign, CT and MR are appropriate first-line imaging techniques.

Abstract

Advances in measurement of thyroglobulin (Tg) and in imaging techniques including high resolution ultrasound, magnetic resonance imaging (MRI), computed tomography (CT), and positron emission tomography (PET) scan have increased our ability to detect thyroid cancer recurrences at an earlier stage. (1,2) After thyroidectomy, patients are often treated with radioiodine, but the recurrent cancers may not image with radioiodine. In these instances, the only definitive treatment is surgical resection. Reoperative neck surgery can be challenging, especially when trying to find a small cancer nodule within the central neck that contains dense fibrotic scar tissue. Herein we describe the use of intraoperative ultrasonography to identify the location of recurrent thyroid cancer. This technique can aid in tumor localization and may help to avoid complications such as recurrent nerve injury.

Abstract

Tissue harmonic imaging (THI) is a new gray-scale sonographic technique that improves image clarity. Harmonics form within the insonated tissue as a consequence of nonlinear sound propagation. Imaging with endogenously formed harmonics means that the distorting layer of the body wall is traversed only once by the harmonic beam--during echo reception. Both image contrast and lateral resolution are improved in harmonic mode compared with conventional (fundamental mode) sonography. This article summarizes the physics and various implementations of harmonic imaging mode, and reviews the clinical applications that have emerged to date.

Abstract

We describe our technique for ultrasonographically guided fine-needle aspiration biopsy of the thyroid that achieves a high rate of diagnostic specimens. Indications for ultrasonographically guided fine-needle aspiration biopsy included a difficult-to-palpate thyroid nodule and previously unsuccessful palpation-guided fine-needle aspiration. Ultrasonographically guided fine-needle aspiration biopsy was performed on 316 thyroid nodules in 306 patients. Adequate cytologic specimens were obtained in 97.2% of the nodules in which biopsy was performed, with a 2.8% rate of inadequate cellularity. Two helpful aspects of this technique that were thought to improve the overall diagnostic yield were the use of color and power Doppler "vascular mapping" of the nodule just before biopsy and on-site cytologic control.

Abstract

We correlated the sonographic appearance of bowel wall thickening with the acuity of the underlying disease process.Sonograms of thickened bowel walls were reviewed in 37 patients with proven gastrointestinal abnormalities. Sonographic findings were correlated with clinical presentation, endoscopy, histology, laboratory data, barium studies, and CT.Twenty-eight patients presented acutely, and nine patients had chronic or subacute disease processes. Two of the 28 patients had concurrent acute and chronic processes. In 27 of 28 patients with acute processes, the abnormal bowel segments were characterized by an echogenic submucosal layer thicker than 2.5 mm. In contrast, nine patients with chronic or subacute processes had relatively uniform hypoechoic thickening of the bowel wall with loss of visualization of a discrete echogenic submucosal layer. CT was available for comparison in 30 of 37 patients. Of the 28 patients with acute abnormalities, the thickened echogenic submucosal layer on sonography corresponded to either low-attenuation submucosal edema (n = 25) or acute submucosal hemorrhage (n = 3).The finding of a thickened submucosal layer suggests an acute disease process of the bowel and corresponds to either submucosal edema or hemorrhage.

Abstract

An abdominal computed tomographic scan was modified by inserting 10 simulated colonic polyps with use of methods that closely mimic the attenuation, noise, and polyp-colon wall interface of naturally occurring polyps. A shape-based polyp detector successfully located six of the 10 polyps. When settings that enhanced the edge profile of polyps were chosen, eight of 10 polyps were detected. There were no false-positive detections. Shape analysis is technically feasible and is a promising approach to automated polyp detection.

Abstract

To present our early experience with a classification scheme for categorizing focal liver lesions on the basis of the enhancement patterns that they exhibit in the arterial phase of computed tomography (CT) and to determine whether particular enhancement patterns suggest particular diagnoses.The authors reviewed arterial phase CT images in 100 consecutive patients with focal liver lesions, excluding simple cysts. The enhancement pattern of the dominant or representative lesion in each patient was classified into one of five categories-homogeneous, abnormal internal vessels or variegated, peripheral puddles, complete ring, or incomplete ring-by three radiologists blinded to the proved diagnosis. Lesions without enhancement were recorded separately. Agreement was reached by consensus in all cases. Standards of reference included findings at histologic examination, correlative imaging, or clinical and imaging follow-up.Ninety-two percent of the 100 lesions demonstrated arterial phase enhancement. Patterns associated with positive predictive values of 82% or greater and specificity of 80% or greater included abnormal internal vessels or variegated (hepatocellular carcinoma), peripheral puddles (hemangioma), and complete ring (metastasis).The appearance of hepatic lesions in the arterial phase of enhancement has potential use in the determination of specific diagnoses. The classification scheme used in this study may be a useful tool for the interpretation of arterial phase CT studies.

Abstract

To compare computed tomographic (CT) angiography and conventional angiography for determining the success of endoluminal stent-graft treatment of aortic aneurysms.Forty patients underwent conventional angiography and CT angiography following treatment of aortoiliac aneurysms with endoluminal stent-grafts. Six additional sets of conventional angiographic-CT angiographic examinations were performed in five patients after placement of additional stent-grafts or coil embolization to treat perigraft leakage. Three faculty CT radiologists who were blinded to patient clinical data and outcome independently interpreted the CT angiograms, and three faculty angiographers, who were not involved in the stent-graft deployment, interpreted the conventional angiograms. Images were assessed for the presence of postdeployment complications. A reference standard was developed by experienced radiologists using all available images and clinical data. Sensitivities, specificities, and kappa values were calculated.Perigraft leakage was the most commonly identified complication. Twenty perigraft leaks were detected in the results of 46 examinations. Sensitivities and specificities for detecting perigraft leakage were 63% and 77% for conventional angiography and 92% and 90% for CT angiography, respectively. The kappa value was 0. 41 for conventional angiography and 0.81 for CT angiography.CT angiography is the preferred method for establishing the presence of perigraft leakage following treatment of aortoiliac aneurysms with stent-grafts.

Abstract

The purpose of this study was to demonstrate the limitations to the effectiveness of CT colonography, colloquially called virtual colonoscopy (VC), for detecting polyps in the colon and to describe a new technique, map projection CT colonography using Mercator projection and stereographic projection, that overcomes these limitations.In one experiment, data sets from nine patients undergoing CT colonography were analyzed to determine the percentage of the mucosal surface visible in various visualization modes as a function of field of view (FOV). In another experiment, 40 digitally synthesized polyps of various sizes (10, 7, 5, and 3.5 mm) were randomly inserted into four copies of one patient data set. Both Mercator and stereographic projections were used to visualize the surface of the colon of each data set. The sensitivity and positive predictive value (PPV) were calculated and compared with the results of an earlier study of visualization modes using the same CT colonography data.The percentage of mucosal surface visualized by VC increases with greater FOV but only approaches that of map projection VC (98.8%) at a distorting, very high FOV. For both readers and polyp sizes of > or =7 mm, sensitivity for Mercator projection (87.5%) and stereographic projection (82.5%) was significantly greater (p < 0.05) than for viewing axial slices (62.5%), and Mercator projection was significantly more sensitive than VC (67.5%). Mercator and stereographic projection had PPVs of 75.4 and 78.9%, respectively.The sensitivity of conventional CT colonography is limited by the percentage of the mucosal surface seen. Map projection CT colonography overcomes this problem and provides a more sensitive method with a high PPV for detecting polyps than other methods currently being investigated.

Abstract

Since its clinical introduction in 1991, volumetric computed tomography scanning using spiral or helical scanners has resulted in a revolution for diagnostic imaging. In addition to new applications for computed tomography, such as computed tomographic angiography and the assessment of patients with renal colic, many routine applications such as the detection of lung and liver lesions have substantially improved. Helical computed tomographic technology has improved over the past eight years with faster gantry rotation, more powerful X-ray tubes, and improved interpolation algorithms, but the greatest advance has been the recent introduction of multi detector-row computed tomography scanners. These scanners provide similar scan quality at a speed gain of 3-6 times greater than single detector-row computed tomography scanners. This has a profound impact on the performance of computed tomography angiography, resulting in greater anatomic coverage, lower iodinated contrast doses, and higher spatial resolution scans than single detector-row systems.

Abstract

To determine the accuracy of helical computed tomography (CT) without the oral, intravenous, or rectal administration of contrast material in confirming suspected acute appendicitis.Three hundred consecutive patients referred from the departments of surgery and emergency medicine were examined for suspected acute appendicitis by using thin-section nonenhanced helical CT. All transverse CT scans were obtained in a single breath hold from the upper abdomen (T12 vertebra) to the pubic symphysis with 5-mm collimation and a pitch of 1.6. All scans were obtained without oral, intravenous, or rectal contrast material. Criteria for diagnosis of acute appendicitis included an enlarged appendix (> 6 mm) and periappendiceal inflammation. CT diagnoses were recorded prospectively. Final diagnoses were established with the results of surgical or clinical follow-up or both.There were 110 true-positive diagnoses, 181 true-negative diagnoses (63 of which were an alternative diagnosis correctly established prospectively), five false-negative diagnoses, and four false-positive diagnoses, which yielded a sensitivity of 96%, a specificity of 99%, and an accuracy of 97%.Nonenhanced helical CT is a highly accurate technique for diagnosing or excluding acute appendicitis. Developing experience with the technique and understanding the subtleties of interpretation can further improve diagnostic accuracy.

Abstract

The authors present case reports demonstrating the trilevel utility of the inferiorly based rectus abdominis musculocutaneous flap in the closure of complex wounds involving the pelvis, groin, and femur that had failed previously or were not amenable to traditional closure techniques. The use of the rectus abdominis flap was especially advantageous for achieving infection eradication and large dead space closure. Additionally they present the emerging technique of power color Doppler imaging as a valuable tool in preoperative flap planning. This technique is particularly useful in evaluating the candidacy for rectus abdominis musculocutaneous flap placement of patients with a prior history of abdominal surgeries, trauma, infection, irradiation, or other conditions that might compromise the patency of the deep inferior epigastric vessels.

Abstract

High-resolution ultrasound and technetium Tc 99m sestamibi scanning can be used for preoperative localization of abnormal parathyroid glands in patients with hyperparathyroidism.Ultrasound and sestamibi scanning were performed in patients undergoing neck exploration for hyperparathyroidism. If the 2 scans agreed in identifying a single adenoma, and surgery confirmed the location of a single adenoma and an ipsilateral normal gland, a unilateral exploration was performed.University tertiary care center.Sixty-one consecutive patients undergoing surgery for hyperparathyroidism from September 1, 1994, through September 30, 1997.High-resolution ultrasound was performed in 59 patients and sestamibi scanning in 58 patients; all patients underwent neck exploration by a single surgeon.The results of preoperative ultrasound and sestamibi scanning were compared with operative and histological findings.All patients were cured of hypercalcemia. Specificity of ultrasound and sestamibi scanning was 98% and 99%, respectively; however, their sensitivity was only 57% and 54%, respectively. Both imaging modalities had lower sensitivities in the setting of multigland disease. If both imaging studies were considered as a single test, sensitivity for imaging in patients with primary hyperparathyroidism reached 78%. Our localization protocol allowed a unilateral approach in 43% of patients (23 of 53).These results confirm the value of preoperative localization in patients with hyperparathyroidism. A unilateral approach can be used with a high degree of success in cases when ultrasound and sestamibi scanning agree in the identification of a single adenoma confirmed by surgical exploration with the identification of a normal ipsilateral gland.

Abstract

To determine the sensitivity of radiologist observers for detecting colonic polyps by using three different data review (display) modes for computed tomographic (CT) colonography, or "virtual colonoscopy."CT colonographic data in a patient with a normal colon were used as base data for insertion of digitally synthesized polyps. Forty such polyps (3.5, 5, 7, and 10 mm in diameter) were randomly inserted in four copies of the base data. Axial CT studies, volume-rendered virtual endoscopic movies, and studies from a three-dimensional mode termed "panoramic endoscopy" were reviewed blindly and independently by two radiologists.Detection improved with increasing polyp size. Trends in sensitivity were dependent on whether all inserted lesions or only visible lesions were considered, because modes differed in how completely the colonic surface was depicted. For both reviewers and all polyps 7 mm or larger, panoramic endoscopy resulted in significantly greater sensitivity (90%) than did virtual endoscopy (68%, P = .014). For visible lesions only, the sensitivities were 85%, 81%, and 60% for one reader and 65%, 62%, and 28% for the other for virtual endoscopy, panoramic endoscopy, and axial CT, respectively. Three-dimensional displays were more sensitive than two-dimensional displays (P < .05).The sensitivity of panoramic endoscopy is higher than that of virtual endoscopy, because the former displays more of the colonic surface. Higher sensitivities for three-dimensional displays may justify the additional computation and review time.

Abstract

To develop and validate a method for the insertion of digitally synthesized polyps into computed tomographic (CT) images of the human colon for use as ground truth for evaluation of virtual colonoscopy.Spiral CT simulator software was used to generate 10 synthetic polyps in various configurations. Additional software was developed to insert these polyps into volume CT scans. Ten polyps in eight patients were selected for comparison. Three radiologists evaluated whether two-dimensional (2D) CT images and three-dimensional (3D) volume-rendered CT images showed synthetic or real polyps.Edge-response profiles and noise of simulated polyps matched those of native polyps. Frequency distributions of reviewers' responses were not significantly different for synthetic versus real polyps in either 3D or 2D images. Responses were clustered around the response of "unsure" if lesions were real or synthetic. Receiver operating characteristic curves had areas of 0.54 (95% CI = 0.39, 0.68) for 3D and 0.39 (95% CI = 0.25, 0.53) for 2D images, which were not significantly different from random guessing (P = .70 and .28 for 3D and 2D images, respectively).Synthetic polyps were indistinguishable from real polyps. This method can be used to generate ground truth experimental data for comparison of CT colonographic display and detection methods.

Abstract

Although malignant fibrous histiocytoma (MFH) is a common sarcoma of late adulthood, it has rarely been reported to involve the pancreas. We describe the clinical and imaging features of a 27-year-old patient presenting with a predominantly cystic MFH. The cystic appearance of the lesion corresponded histologically to necrosis and hemorrhage within the mass.

Abstract

We present a technique for obtaining three-dimensional external and virtual endoscopy views of organs using perspective volume-rendered gray-scale and Doppler sonographic data, and we explore potential clinical applications in the carotid artery, the female pelvis, and the bladder.Using the proposed methods, radiologists will find it possible to create virtual endoscopy and external perspective views using sonographic data. The technique works well for revealing the interior of fluid-filled structures and cavities. However, expected improvements in computer performance and integration with existing sonographic equipment will be necessary for the technique to become practical in the clinical environment.

Abstract

We evaluated the usefulness of power Doppler imaging (PDI) in diagnosing acute renal-transplant rejection.Twenty-eight patients underwent 33 renal-transplant biopsies for suspected acute rejection. Patterns of renal parenchymal vascularity revealed by PDI in patients with abnormal biopsy results were compared with patterns in a group who had normal biopsy results. PDI examinations were reviewed retrospectively by 2 independent radiologists who had no knowledge of the biopsy results. A PDI diagnosis of acute rejection required marked vascular pruning in both the cortex and medulla. PDI results then were compared with transplant-biopsy results.The sensitivity and specificity of PDI for diagnosing acute renal-transplant rejection were 40% and 100%, respectively. None of the patients with negative biopsy results had PDI abnormalities. The negative predictive value of PDI was 33%, and the positive predictive value was 100%.In our study, an abnormal sonogram was highly predictive of acute transplant rejection. However, a normal sonogram did not exclude the possibility of rejection.

Abstract

Currently, CT plays a pivotal role in the evaluation of the patient with an acute abdomen. Several competing techniques have been described and investigated. Each appears to possess advantages and disadvantages which will be examined. Each imaging center needs to modify these protocols to satisfy local scanner availability, patient demographics, radiologic expertise, and economic considerations.

Abstract

A case of an hepatic abscess that developed after percutaneous transhepatic drainage of a subphrenic abscess is presented. The location of the abscess immediately along the tract of the drainage catheter and the similar organisms recovered from bacteriologic culture suggest that the abscess was related to direct contamination along the tract of the drainage catheter. The potential for abscess formation within the liver should be considered in the choice of access route for percutaneous drainage of retroabdominal abscesses. It may be preferable to avoid transhepatic drainage in patients in whom it is anticipated that the catheter drainage will require considerable length of time.

Abstract

CT angiography (CTA) is a minimally invasive technique that has proven to be clinically useful in evaluating the vasculature of the abdominal viscera. In many instances, the diagnostic information obtained from abdominal CTA is sufficient to avoid the expense and morbidity of conventional angiography. This article reviews the indications, technique, and pitfalls of abdominal CTA with specific emphasis on disorders of the hepatic, splenic, and superior mesenteric arteries and the portal venous system.

Abstract

Evaluation of the abdominal and thoracic aorta is one of the most common indications for CT angiography (CTA). CTA largely has replaced conventional angiography in the assessment of aortic aneurysms and dissections because it provides all the relevant anatomic information at reduced cost, morbidity, and radiation exposure. This article will focus on the technique, interpretation, and pitfalls in the CTA evaluation of the abdominal and thoracic aorta.

Abstract

The objective of our study was to determine the value of using color and power Doppler sonography to reveal extrathyroidal feeding arteries in the detection of abnormal parathyroid glands.Forty-four patients with primary hyperparathyroidism were imaged prospectively with high-resolution gray-scale, color flow, and power Doppler sonography. The presence of extrathyroidal arteries supplying the adenomas was noted. All patients underwent subsequent neck exploration. The locations of the abnormal glands were recorded.At surgery, 51 abnormal parathyroid glands were removed in the 44 patients. Sonography correctly revealed an adenoma in 40 of the 44 patients. Likewise, sonography revealed 42 of the 51 adenomas. Nine false-negative and two false-positive interpretations of the sonograms were made. Thus, overall sensitivity was 83%, specificity was 98%, and accuracy was 94%. Three of the false-negative interpretations were ectopic glands within the superior mediastinum. Excluding these three glands from analysis, the sensitivity for detection of adenomas within the neck was 88%, specificity was 98%, and accuracy was 95%. An extrathyroidal artery leading to a parathyroid adenoma was seen in 35 of the 42 adenomas revealed by sonography. The presence of an extrathyroidal artery leading to an adenoma was found to aid in the detection of an otherwise inconspicuous parathyroid gland in five patients, which improved sensitivity from 73% to 83%.Prominent vessels supplying parathyroid adenomas are frequently revealed by color flow and power Doppler sonography. These vessels can serve as "road maps" to abnormal parathyroid glands.

Abstract

Virtual colonoscopy is a new method of colon examination in which computer-aided 3D visualization of spiral CT simulates fiberoptic colonoscopy. We used a colon phantom containing various-sized spheres to determine the influence of CT acquisition parameters on lesion detectability and sizing.Spherical plastic beads with diameters of 2.5, 4, 6, 8 and 10 mm were randomly attached to the inner wall of segments of plastic tubing. Groups of three sealed tubes were scanned at 3/1, 3/2, 5/1 collimation (mm)/pitch settings in orientations perpendicular and parallel to the scanner gantry. For each acquisition, image sets were reconstructed at intervals from 0.5 to 5.0 mm. Two blinded reviewers assessed transverse cross-sections of the phantoms for bead detection, using source CT images for images for acquisitions obtained with the tubes oriented perpendicular to the gantry and using orthogonal reformatted images for scans oriented parallel to the gantry.Detection of beads of > or = 4 mm was 100% for both tube orientations and for all collimator/pitch settings and reconstruction intervals. For the 2.5 mm beads, detection decreased to 78-94% for 5 mm collimation/pitch 2 scans when the phantom sections were oriented parallel to the gantry (p = 0.01). Apparent elongation of beads in the slice direction occurred as the collimation and pitch increased. The majority of the elongation (approximately 75%) was attributable to changing the collimator from 3 to 5 mm, with the remainder of the elongation due to doubling the pitch from 1 to 2.CT scanning at 5 mm collimation and up to pitch 2 is adequate for detection of high contrast lesions as small as 4 mm in this model. However, lesion size and geometry are less accurately depicted than at narrower collimation and lower pitch settings.

Abstract

In this paper, a novel technique for rapid and automatic computation of flight paths for guiding virtual endoscopic exploration of three-dimensional medical images is described. While manually planning flight paths is a tedious and time consuming task, our algorithm is automated and fast. Our method for positioning the virtual camera is based on the medial axis transform but is much more computationally efficient. By iteratively correcting a path toward the medial axis, the necessity of evaluating simple point criteria during morphological thinning is eliminated. The virtual camera is also oriented in a stable viewing direction, avoiding sudden twists and turns. We tested our algorithm on volumetric data sets of eight colons, one aorta and one bronchial tree. The algorithm computed the flight paths in several minutes per volume on an inexpensive workstation with minimal computation time added for multiple paths through branching structures (10%-13% per extra path). The results of our algorithm are smooth, centralized paths that aid in the task of navigation in virtual endoscopic exploration of three-dimensional medical images.

Abstract

The purpose of this study was to determine the impact of ultrasound-guided fine-needle aspiration biopsy (USFNA) in the cytological diagnosis of nodular thyroid disease. It remains unclear exactly what role USFNA should play in the cytological diagnosis of nodular thyroid disease. All patients who underwent fine-needle aspiration (FNA) for nodular thyroid disease at Stanford University Medical Center from 1991 to 1996 were included in the study. Histopathologic diagnoses were compared to cytological diagnoses for those patients who underwent surgery. FNA was performed on a total of 497 thyroid nodules. Palpation-guided FNA (pFNA) was performed on 370 nodules, and USFNA was done on 127. The USFNAs were performed for the following reasons: 95 (75%) for nonpalpable or difficult-to-palpate nodules; 14 (11%) for previously failed FNA; and 18 (14%) for incidentally detected nodules. FNA had an unsuccessful biopsy rate of 16% and a sensitivity and specificity of 89% and 69%, respectively. USFNA had an unsuccessful biopsy rate of 7% and a sensitivity and specificity of 100% and 100%, respectively. The cancer yield at surgery for pFNA was 40%, and the cancer yield at surgery for USFNA was 59%. The complementary use of USFNA with pFNA improves the diagnostic approach to nodular thyroid disease. The use of USFNA has increased the cancer yield at surgery and the sensitivity of thyroid biopsy at our institution.

Abstract

Dual-phase helical CT permits imaging of the pancreas and the peripancreatic structures in the arterial dominant and portal venous phases of enhancement, providing information crucial in the assessment of the local extent of pancreatic adenocarcinoma. This essay reviews the dual-phase helical CT findings of local extension that preclude potentially curative surgery, including vascular involvement, ligamentous or mesenteric invasion, extension of the tumor to involve the stomach or duodenum, and invasion of adjacent solid organs.

Abstract

We assessed the utility of power Doppler imaging (PDI) in preoperative planning and postoperative evaluation of microvascular tissue transfers.Twenty-five PDI studies were performed on 23 patients using a 5-10-MHz linear-array transducer. Thirteen patients were assessed preoperatively for patency of the desired donor vessel; 8 of them had surgical scars overlying the desired vascular territory. Twelve patients (including 2 from the first group) were evaluated postoperatively for patency of the vascular anastomoses and adequacy of the blood supply to the transferred tissue.Twelve of the 13 patients assessed preoperatively had successful flap transfers. Four of the 8 patients with scars over the desired vascular territories had absent or aberrant arteries, necessitating a change in the operative plan. None of these patients had operative complications. Eight of the 12 patients scanned postoperatively had patent anastomoses. In 2 of these patients, impending surgery was averted when the adequacy of the tissue blood supply was established with PDI. In 4 patients, PDI showed arterial or venous compromise, which was confirmed at surgery.PDI is a useful technique in microsurgical tissue transfer for assessing the patency of desired donor vessels preoperatively and for postoperative evaluation of blood supply.

Abstract

The purpose of our study was to assess the potential of power Doppler imaging (PDI) to differentiate benign from malignant solid breast masses.Sixty-nine biopsy-proven solid breast masses were evaluated with PDI using 7- to 10-MHz transducers optimized for low-volume flow sensitivity. The extent of flow on PDI was estimated as a percentage of the lesion area on multiple longitudinal and transverse static sonographic images. Flow was categorized as avascular; less than 10%; 10-25%; 25.1-50%; and greater than 50%.Of the 69 lesions evaluated, 33 were malignant and 36 were benign. Of the avascular lesions, nine were malignant and eight were benign. Significant overlap was seen in the vascularity of the other 52 lesions: both malignant and benign lesions revealed a similar range of vascular patterns.Preliminary experience with PDI suggests that both malignant and benign lesions can be avascular and that the presence of color within a solid breast mass is a nonspecific finding. Assessing the extent of vascularity with PDI appears to be of limited value in the diagnostic evaluation of solid breast masses.

Abstract

To evaluate factors associated with acalculous cholecystitis in patients undergoing bone marrow transplantation and the role of repeat ultrasound examinations.Retrospective study.University hospital, United States.381 Patients who underwent bone marrow transplantation between 1987 and 1992.Abdominal ultrasound examination (n = 134), repeat ultrasound in those considered to have acalculous cholecystitis (n = 8), and acute cholecystectomy (n = 5).14 Patients (4%) with acalculous cholecystitis were identified. The 8 who had had liver tissue examined also had veno-occlusive disease of the liver. It was possible to follow progressing or resolving acalculous cholecystitis by repeat ultrasound examinations. 4 Of the 5 patients treated surgically survived, compared with 3 of the 9 not operated on.Acalculous cholecystitis was associated with veno-occlusive disease of the liver. Repeat ultrasound examinations were valuable in showing progressing or resolving acalculous cholecystitis and may guide treatment. Cholecystectomy seems to be a safe procedure for acalculous cholecystitis in patients undergoing bone marrow transplantation.

Abstract

The improved depiction of renal parenchymal vascularity with power Doppler imaging facilitates the sonographic detection of hypovascular lesions such as pyelonephritis, renal abscesses, and infarction. However, the finding of diminished or absent lobar perfusion may be present in all of these entities; thus, the abnormalities shown on power Doppler imaging are often nonspecific. Clinical and laboratory data are often essential to establish the correct diagnoses. Contrast-enhanced CT remains useful for distinguishing these various disorders.

Abstract

The purpose of this study was to evaluate the abdominal CT findings in patients with spontaneous intramural small bowel haemorrhage. We retrospectively reviewed the abdominal CT scans of six patients with known intramural small bowel haemorrhage. All of the patients had an underlying coagulopathy. All six patients underwent CT examinations without oral or intravenous contrast media. All six non-contrast CT scans showed hyperattenuation of the involved bowel segments, with thickened and dilated proximal small bowel. Therefore, patients who are clinically at risk for intramural small bowel haemorrhage should undergo a non-contrast CT scan of the abdomen prior to the routine oral and intravenous contrast-enhanced scan. In most cases the non-contrast scan will provide definitive diagnostic information which may not be evident from the contrast-enhanced scan alone.

Abstract

Our goal was to determine if arterial phase images from dual phase helical CT improve either the detection or the characterization of hepatic metastases in patients with colorectal carcinoma. Sixty-two patients with known colorectal cancer underwent 65 dual phase helical CT examinations to evaluate for possible liver metastases. Three blinded reviewers independently evaluated the portal venous phase images alone to determine if hepatic metastases were present or absent. Arterial phase images were then analyzed to determine if they identified additional lesions or aided in characterizing small hepatic lesions. Scores of the two methods for diagnosing metastases were compared with the "gold standard" established by a consensus panel of three other radiologists who reviewed all images together with clinical, pathologic, and other imaging data. The addition of arterial phase imaging did not detect any new metastases. However, in 6 of the 64 technically adequate examinations, hepatic arterial phase images increased lesion conspicuity and significantly increased diagnostic confidence when compared with portal vein phase scans alone. In patients with colorectal cancer, the addition of arterial phase imaging does not increase sensitivity, but improves the specificity in diagnosing liver metastases in a small number of cases. Dual phase helical CT does not appear to be indicated in the evaluation of liver metastases from colorectal cancer.

Abstract

The purposes of this investigation were to compare prospectively the pattern and extent of cystic artery flow revealed by power Doppler sonography and color Doppler sonography in patients with normal gallbladders and to analyze the potential implications of these findings for power Doppler sonography in diagnosing acute cholecystitis.The cystic arteries of 142 patients (79 women and 63 men) with normal gallbladders were imaged with both power Doppler sonography and color Doppler sonography using 5-MHz transducers and settings optimized to reveal low-volume flow. The presence or absence of cystic artery flow and the anatomic extent of its visualization were recorded for each patient.Power Doppler sonography revealed flow in 73% of patients with normal gallbladders compared with 53% revealed by color Doppler sonography. Cystic artery flow within the distal fundal quartile was revealed by power Doppler sonography in 20% of patients and flow spanning greater than 50% of the anterior gallbladder wall was revealed by power Doppler sonography in 17% of patients. These findings differed from those of color Doppler sonography at a highly significant level (p < .0001, chi-square test).Power Doppler sonography is significantly more sensitive than color Doppler sonography for revealing cystic artery flow in patients with normal gallbladders. The flow patterns in patients with normal gallbladders obtained with power Doppler sonography overlap flow patterns previously reported as fairly specific criteria for diagnosing acute cholecystitis using color Doppler sonography, namely, flow within the distal fundal quartile and flow spanning greater than 50% of the anterior gallbladder wall. Accordingly, these color Doppler sonography criteria are not applicable to the diagnosis of acute cholecystitis with power Doppler sonography. Different power Doppler sonography criteria are necessary for the diagnosis of acute cholecystitis.

Abstract

The space below the kidneys where the anterior and posterior pararenal spaces converge has been defined only vaguley in the past. We describe observations on clinical CT cases and studies on cadavers that lead to a refinement in the terminology for this extraperitoneal compartment.Abdominal/pelvic CT scans from 18 patients and the scans of 2 cadavers injected in the femoral region with iodinated contrast material were reviewed concerning the location and distribution of fluid or gas collections relative to the renal fascial enclosure.Pathologic processes involving the anterior or posterior pararenal spaces in addition to the pelvic extraperitoneal spaces were always accompanied by collections in the space below the cone of renal fascia.The term infraconal compartment is a suggested term for the caudal continuation of the anterior and posterior pararenal spaces. This compartment serves as an important multidirectional pathway for the spread of disease between the extraperitoneal abdomen and the pelvis. Fluid collections within this compartment have a characteristic CT appearance.

Abstract

The purpose of this study was to determine the diagnostic accuracy of unenhanced helical CT scans in patients with a suspected acute appendicitis.Over a 20-month period, 109 adult patients with suspected acute appendicitis were referred by the emergency department for an unenhanced helical CT scan. Each scan was obtained in a single breath-hold from the T12 vertebral body to the public symphysis using a 5-mm collimation and a pitch of 1.6. No patients were given oral or IV contrast media. The primary CT criteria for diagnosing acute appendicitis was the identification of an appendix with a transverse diameter larger than 6 mm with associated periappendiceal inflammatory changes. The presence of an appendicolith was considered a secondary finding as was isolated periappendiceal inflammation; however, appendicitis was not diagnosed in such patients unless an enlarged appendix was definitely identified. Final diagnoses were established by surgical or clinical follow-up and were compared with the original CT reports.We found 66 true-negatives, 37 true-positives, four false-negatives, and two false-positives that yielded a sensitivity of 90%, a specificity of 97%, a positive predictive value of 95%, a negative predictive value of 95%, and an accuracy of 94%. An alternative diagnosis was established by an unenhanced helical CT scan in 24 patients (22%), which included cecal diverticulitis (seven patients), urinary tract disease (five patients), adnexal pathology (four patients), sigmoid diverticulitis (two patients), small bowel disease (three patients), right lower quadrant tumor (two patients), and an infected dialysis catheter (one patient).Unenhanced thin-section helical CT is an accurate, effective technique for diagnosing acute appendicitis.

Abstract

To use perspective volume rendering (PVR) of computed tomographic (CT) and magnetic resonance (MR) imaging data sets to simulate endoscopic views of human organ systems.Perspective views of helical CT and MR images were reconstructed from the data, and tissues were classified by assigning color and opacity based on their CT attenuation or MR signal intensity. "Flight paths" were constructed through anatomic regions by defining key views along a spline path. Twelve movies of the thoracic aorta (n=3), tracheobronchial tree (n=4), colon (n=3), paranasal sinuses (n=1), and shoulder joint (n=1) were generated to display images along the flight path. All abnormal results were confirmed at surgery.PVR fly-through enabled evaluation of the full range of tissue densities, signal intensities, and their three-dimensional spatial relationships.PVR is a novel way to present volumetric data and may enable noninvasive diagnostic endoscopy and provide an alternate method to analyze volumetric imaging data for primary diagnosis.

Abstract

The purpose of this study was to analyze variations in the lateral contour of the head and neck of the pancreas that can mimic pancreatic masses on CT imaging.We retrospectively reviewed dual-phase helical CT examinations of 119 patients who had no clinical or CT evidence of pancreatic disease. Contour variations of the head and neck of the pancreas were analyzed and were classified according to their anatomic orientation.Forty-one (34.5%) of the 119 patients had discrete lobulations of pancreatic tissue greater than 1 cm lateral to the gastroduodenal or anterior superior pancreaticoduodenal artery. These lobulations showed normal pancreatic density on both predominantly arterial and portal venous phase images. Contour variants of the pancreatic head and neck were categorized as three main types: anterior (type I), posterior (type II), and horizontal (type III). In the 119 patients, we found 12 type I variants (10%), 23 type II variants (19%), and six type III variants (5%).Variations in the lateral contour of the normal head and neck of the pancreas are common. Recognition of the different types of contours may help avoid misinterpretation of normal variants as pancreatic masses.

Abstract

Expeditious diagnosis and treatment of pancreatic injury continues to elude the trauma surgeon and radiologist. Missed or underestimated pancreatic injury is responsible for a high level of morbidity and mortality after blunt or penetrating trauma. Unfortunately, inappropriate therapy can lead to devastating consequences such as severe endocrine or exocrine insufficiency. Abdominal CT is currently the imaging method of choice for evaluating patients with blunt trauma. This article reviews the constellation of CT findings that the radiologist must rely on to establish the diagnosis of pancreatic injury.

Abstract

The purpose of our study was to assess the prevalence and risk factors for sonographically detectable lower extremity deep venous thrombosis (DVT) in asymptomatic patients following major orthopedic surgery.We performed color Doppler sonography of the lower extremities in 474 asymptomatic patients following major hip or knee surgery. We determined the prevalence of lower extremity DVT and used stepwise logistic regression to identify factors predictive of DVT. All patients received routine prophylactic measures.The prevalence of DVT was 7%. Laterality of surgery, age, and gender were all independent predictors of DVT (p < or = .01): the odds of having DVT were 20 times higher in the leg that was operated upon than in the leg that was not; the odds of DVT rose by a factor of 1.5 per decade of life; and the odds of DVT were 3.4 times greater in men than in women. DVT was more common in patients who had received general rather than epidural anesthesia, with borderline significance (p = .06). The length of anesthesia and the joint involved (hip or knee) were not predictive of DVT (p > .10).Despite prophylaxis, DVT is a relatively common postoperative complication in patients who undergo major orthopedic procedures. Routine screening for DVT is warranted in asymptomatic patients who have undergone hip or knee surgery, and color Doppler sonography, despite its limitations, offers a reasonably accurate noninvasive method for screening these patients. Subsets of patients who are at particular risk include the elderly, male patients, and patients who have undergone general anesthesia. The low prevalence of DVT in limbs not operated upon suggests that routine screening may be limited to evaluating the affected limbs only, thus helping to minimize the cost of screening.

Abstract

To compare the usefulness of power Doppler imaging and color Doppler imaging in the vascular evaluation of gastrointestinal lesions, 21 patients with focal gastrointestinal tract lesions were examined with both power and color Doppler imaging. Two reviewers blinded to the diagnosis compared intramural vascularity detected by each of these methods. Power Doppler imaging detected flow in 16 patients with nonischemic lesions, whereas color Doppler imaging detected flow in only 11 patients. Neither modality detected flow in three patients with transmural infarction, but only power Doppler imaging detected minimal flow in the two patients with reversible ischemia. Power Doppler imaging improves visualization of intramural gastrointestinal vascularity, increasing the level of confidence in differentiating ischemic from nonischemic lesions.

Abstract

Most patients presenting with right lower quadrant pain are clinically suspected to have acute appendicitis. However, sonographic findings other than appendicitis are detected in patients who are referred for ultrasound to rule out appendicitis. This pictorial essay delineates a number of unsuspected pathological conditions revealed by ultrasound examination of the right lower quadrant that do not involve the appendix but closely mimic acute appendicitis. Imaging studies play a significant role in preoperative diagnosis and determination of proper treatment. The patient can undergo triage for proper further workup and surgical versus nonsurgical management. Acute appendicitis initially was considered on clinical presentation in all of our patients. The correct diagnosis of other pathological conditions was made on the basis of sonographic findings.

Abstract

The present study reviews four cases in which degenerated uterine leiomyomas mimicked appendicitis clinically. The correct diagnosis was made prospectively by sonography in each case. Appendicitis was excluded by graded compression sonography and an exophytic uterine leiomyoma was identified at the point of maximal symptoms. The leiomyomas demonstrated central hypoechoic foci, but no detectable Doppler flow indicating necrosis. Although the phenomenon of a degenerated uterine leiomyoma mimicking appendicitis clinically is known, sonographic diagnosis has not been reported previously. The importance of making this diagnosis sonographically is that management of a degenerated leiomyoma is conservative and unnecessary surgery could be avoided.

Abstract

The purpose of this study was to determine the value of reformatted noncontrast helical CT in patients with suspected renal colic. We hoped to determine whether this technique might create images acceptable to both radiologists and clinicians and replace our current protocol of sonography and abdominal plain film.Thirty-four consecutive patients with signs and symptoms of renal colic were imaged with both noncontrast helical CT and a combination of plain film of the abdomen and renal sonography. Reformatting of the helical CT data was performed on a workstation to create a variety of reformatted displays. The correlative studies were interpreted by separate blinded observers. Clinical data, including the presence of hematuria and the documentation of stone passage or removal, were recorded.Findings on 18 CT examinations were interpreted as positive for the presence of ureteral calculi; 16 of these cases were determined to be true positives on the basis of later-documented passage of a calculus. Thirteen of the 16 cases proved to be positive were interpreted as positive for renal calculi using the combination of abdominal plain film and renal sonography. The most useful CT reformatting technique was curved planar reformatting of the ureters to determine whether a ureteral calculus was present.In this study, noncontrast helical CT was a rapid and accurate method for determining the presence of ureteral calculi causing renal colic. The reformatted views produced images similar in appearance to excretory urograms, aiding greatly in communicating with clinicians. Limitations on the technique include the time and equipment necessary for reformatting and the suboptimal quality of reformatted images when little retroperitoneal fat is present.

Abstract

To determine whether spiral computed tomography (CT) can be used to evaluate potential living renal donors.Twelve potential living renal donors underwent spiral CT and conventional arteriography. CT angiography was performed with 30-second spiral acquisition during injection of 150 mL of nonionic iodinated contrast material into an antecubital vein at 5 mL/sec. Five minutes after injection, a frontal abdominal scout projection was obtained to assess the renal collecting system. Results of blinded interpretations of axial CT angiograms, three-dimensional CT angiograms, and conventional arteriograms were correlated with intraoperative findings in 11 cases.Axial and three-dimensional CT angiography were 100% sensitive for identifying seven accessory renal arteries and 14% and 93% sensitive for identifying five prehilar renal artery branches. Renal venous anomalies were confirmed in three patients at surgery. Operative management changed in four of 11 patients who underwent donor nephrectomy.Spiral CT holds promise as a single examination for anatomic assessment of living renal donors.

Abstract

To determine the improvement in pancreatic enhancement at helical computed tomography (CT) performed with an early delay after administration of contrast material compared with that performed with a standard delay.Dual-phase helical CT of the abdomen was performed in 120 patients with a 150-mL bolus of contrast material infused at 5 mL/sec. Early and standard delayed scanning was performed beginning at 20 seconds and 49-71 seconds, respectively. Regions of interest were measured in the head, body, and tail of the pancreas in 92 patients. The difference in enhancement between early and standard delayed scanning was calculated.Mean pancreatic enhancement was 82 HU +/- 3 (standard error) with an early delay, whereas enhancement on standard delay scans was 62 HU +/- 2 (P < .001). An improvement in enhancement greater than 10 HU was attained in 66 of 92 cases (72%).Pancreatic enhancement at helical CT with an early delay after contrast material administration is often significantly greater than the enhancement seen with a standard delay when a monophasic, rapidly infused bolus of contrast material is used.

Abstract

Injuries to the bowel and mesentery are found in approximately 5% of all patients undergoing laparotomy after blunt abdominal trauma. Bowel and mesenteric injuries are often subtle and difficult to diagnose, and a delay in the diagnosis is associated with increased mortality and morbidity. CT is the best imaging method for diagnosing injuries to the bowel and mesentery. With meticulous scanning techniques, most significant bowel and mesenteric injuries can be reliably identified with CT preoperatively, and associated injuries to other abdominal viscera can be confirmed.

Abstract

Helical CT scanners now allow sequential arterial phase and portal venous phase scans of the entire liver to be obtained during a single bolus injection of contrast material. The purpose of this study was to determine if arterial phase scans improve detection of small (< or = 1.5 cm) malignant hepatic neoplasms when compared with portal venous scans alone.Dual-phase helical CT of the liver was done in 96 patients referred for known or suspected malignant hepatic lesions. Malignant hepatic neoplasms were detected in 38 patients (27 with at least one small neoplasm), one patient had undetected metastases, one patient had a benign hepatic neoplasm, and 56 patients had no hepatic neoplasm. Proof of individual neoplasms was based on biopsy results, surgical findings, or findings on other imaging studies (primarily follow-up CT). The absence of disease was established by surgical or autopsy findings, findings on subsequent imaging studies, or a combination of clinical and laboratory data. A total of 150 ml of 60% nonionic contrast material was infused at 5 ml/sec followed by sequential arterial phase and portal venous phase helical scans of the liver. Three radiologists retrospectively reviewed the scans. Individual lesions were measured and the conspicuity of each lesion on arterial phase and portal venous phase scans was compared. The percentage of patients in whom some malignant neoplasms were detected better on the arterial phase scan was calculated using categories based on lesion size and typical tumor vascularity.In 10 (37%) of 27 patients who had at least one small malignant neoplasm, lesions 1.5 cm or less in diameter were only visible or were more conspicuous on the arterial phase scan. No malignant neoplasms more than 1.5 cm in diameter were visible only on the arterial phase scan. In four (11%) of 38 cases, malignant neoplasms more than 1.5 cm in diameter were more conspicuous on the arterial phase scan. The arterial phase scans improved lesion conspicuity in nine (39%) of 23 patients who had typically hypervascular neoplasms, whereas lesion conspicuity was improved in three (20%) of 15 patients who had typically hypovascular neoplasms (p = .02). The arterial phase scan resulted in the false-positive detection of lesions in two (2%) of 96 cases.Arterial phase helical CT of the liver improves detection of some small, malignant hepatic neoplasms when performed in addition to portal venous scanning. The value is greatest in those patients who have hypervascular neoplasms.

Abstract

Both emphysematous pyelonephritis and emphysematous cholecystitis are uncommon, but potentially fatal, clinical entities. The simultaneous diagnosis of these two entities in the same patient has not previously been reported. In this paper, we describe a 68-year-old diabetic male who presented acutely with emphysematous pyelonephritis and emphysematous cholecystitis. This case demonstrates several important diagnostic and treatment considerations. Additionally, the unique circumstances of this case offer support for the proposal that emphysematous cholecystitis may often be secondary to hematogenous seeding/embolic phenomena rather than obstruction of the cystic duct. Prompt diagnosis is essential, as prompt intervention can minimize mortality and morbidity.

Abstract

The purpose of this study was to determine the gray-scale and color Doppler sonographic appearance of testicular lymphoma and leukemia to aid in its differentiation from primary testicular neoplasms and inflammatory processes.We retrospectively reviewed the testicular sonograms of eight male patients 5-74 years old (mean age, 43 years) with pathologically proved testicular leukemia or lymphoma. All patients presented with testicular enlargement. Gray-scale sonograms were obtained to determine the presence or absence of a mass, focal nodule, or diffuse infiltration, as well as the degree of parenchymal echogenicity. Color Doppler sonography was applied in each case to determine the degree of vascularity compared with normal ipsilateral or contralateral testicular parenchyma. In patients with focal, measurable lesions, the size was correlated with its color Doppler sonographic appearance.Gray-scale sonograms showed either homogeneously hypoechoic testes in patients with diffuse round-cell infiltration or multifocal hypoechoic lesions of various sizes. Five patients had a total of 11 focal lesions that ranged in size from 8 mm to 26 mm in maximum diameter (mean diameter, 16 mm). Color Doppler sonography revealed increased intralesional flow in all areas of lymphomatous or leukemic involvement irrespective of lesion size.Our results show that testicular lymphoma and leukemia are hypervascular on color Doppler sonograms regardless of the size of the tumor. Although color Doppler sonography may provide useful information, differentiating round-cell infiltration from inflammatory processes of the testes remains difficult.

Abstract

Color Doppler sonography was used to evaluate the length and distribution of the cystic artery in the gallbladder wall in 115 normal adults and in 54 patients with surgically proved cholecystitis. All patients were scanned with a 5 MHz curved array transducer optimized for low volume color sensitivity. A specific attempt was made to visualize the cystic artery throughout its course. Spectral Doppler waveforms were obtained to document arterial flow. The length of the cystic artery visualized was analyzed as a quartile percentage length of the anterior gallbladder wall. The distribution of the cystic artery flow also was analyzed in specific quartiles. Of 54 patients with acute cholecystitis, 26% had cystic artery length greater than half of the anterior gallbladder wall, compared with 2% of 115 normal controls (P < 0.001); 19% of patients with cholecystitis had flow in the distal (fundal) quartile, compared to 0% of normal controls (P < 0.0001). Although the presence or absence of flow in the gallbladder is not a reliable finding to establish the diagnosis of acute cholecystitis, length of cystic artery visualized is a potentially useful criterion to suggest the diagnosis of acute cholecystitis, especially in cases in which flow in the distal fundal quartile of the gallbladder. The usefulness of color Doppler sonography in acute cholecystitis is limited owing to the fact that it is insensitive, and many patients with cholecystitis have no detectable flow or have normal flow patterns.

Abstract

To analyze the color Doppler flow imaging features and clinical importance of inflamed pericholecystic fat.Forty patients with surgically proved right upper quadrant inflammatory lesions in the gallbladder or the pericholecystic space underwent color Doppler sonography (CDS). Findings in the pericholecystic space were correlated with those at computed tomography (CT) in four patients and with surgical findings in 40 patients.CDS performed in 12 (30%) of the 40 patients demonstrated echogenic pericholecystic masses greater than 1 cm in diameter that contained internal vascularity. CT in four patients and surgical findings in all 12 patients demonstrated inflamed fat adherent to the gallbladder.Identification with CDS of inflamed pericholecystic fat may provide preoperative information that could be pertinent in the decision to perform open or laparoscopic cholecystectomy in patients with acute cholecystitis.

Abstract

Magnetic resonance imaging is becoming increasingly useful in characterizing adnexal masses, whereas endovaginal ultrasound is an invaluable technique for examining the uterus and adnexa. This pictorial essay depicts the internal architectural details necessary for characterization of various adnexal masses imaged with both EVU and MR imaging. Forty consecutive examinations that revealed 51 adnexal masses were reviewed. All patients had MR imaging and EVU examinations within 1 week of each other. T1- and T2-weighted images in coronal, axial, and sagittal planes were included. Fat suppression technique also was used in selected cases. EVU, because of its high spatial resolution, was able to depict better internal architectural details, allowing specific diagnosis of most adnexal masses, whereas MR imaging was superior in differentiating hemorrhagic masses from dermoids when specific fat suppression techniques were used.

Abstract

The purpose of this study was to determine the value of detecting fluid between the splenic vein and the pancreas on CT scans in the diagnosis of pancreatic injury after blunt abdominal trauma.We retrospectively reviewed the abdominal CT scans of 10 patients with surgical- or autopsy-proved pancreatic injury after blunt abdominal trauma. The finding of fluid interdigitating between the pancreas and the splenic vein was then studied along with the reported CT features of pancreatic injury. These included intraperitoneal fluid, fluid in the lesser sac, extraperitoneal fluid, pancreatic edema or hematoma, and thickening of the anterior renal fascia.The CT scans of all 10 patients reviewed showed abnormalities suggesting pancreatic injury. Only 40% of patients showed all of the findings reported in the literature. Fluid interdigitating between the splenic vein and the pancreatic parenchyma was seen on CT scans in 90%.Our experience suggests that fluid between the splenic vein and the pancreas is a helpful CT finding for the diagnosis of pancreatic injury after blunt abdominal trauma. This finding was easy to recognize and in the proper clinical setting directs attention to additional subtle findings of pancreatic injury.

Abstract

Graded compression sonography has gained widespread acceptance as a useful technique to evaluate patients with atypical signs and symptoms of appendicitis. When positive, early surgery can be performed prior to perforation. When there is no sonographic evidence of appendicitis, other alternative diagnoses may be established. CT scans and the contrast enema remain the primary imaging modalities to evaluate suspected diverticulitis; however, sonography may be useful in selected patients with an atypical clinical presentation.

Abstract

The purpose of this study was to analyze the usefulness of two specific CT signs of sigmoid mesenteric inflammation (fluid at the root of the mesentery and vascular engorgement) for identifying and differentiating sigmoid diverticulitis from carcinoma.CT scans of 69 patients with surgically proved sigmoid diverticulitis were retrospectively reviewed and compared with CT findings in 29 patients with surgically proved sigmoid carcinoma. Two specific patterns of inflammation of the sigmoid mesentery were analyzed: fluid at the root of the sigmoid mesentery and engorgement of the sigmoid mesenteric vessels.The CT findings were present more often in patients with sigmoid diverticulitis than in those with carcinoma (p < .001). Fluid at the base of the mesentery had a sensitivity, specificity, and positive predictive value for diverticulitis of 36%, 90%, and 89% respectively. Vascular engorgement alone had a sensitivity, specificity, and positive predictive value of 29%, 100%, and 100%, respectively.Our results suggest that CT findings of fluid at the root of the mesentery and vascular engorgement are useful in distinguishing sigmoid diverticulitis from carcinoma of the sigmoid.

Abstract

Graded compression color Doppler sonography was used to evaluate gastrointestinal blood flow in 20 normal fasting subjects and 32 patients with focal gastrointestinal lesions. Imaging was optimized for color sensitivity using a 5 MHz linear array transducer. Criteria were established for normal mural blood flow based on findings in normal controls. Two reviewers blinded to the final diagnosis compared patterns of mural vascularity in normal and abnormal patients. Increased mural blood flow was demonstrated in all 32 patients with gastrointestinal inflammatory disorders and in seven of nine patients with neoplasms. No mural flow was demonstrated in four patients with small bowel infarction. The greatest overall degree of flow was noted in patients with Crohn's disease and cytomegalovirus colitis. Flow in tumors was variable, ranging from strikingly increased flow in a giant villoglandular polyp to absent flow in a metastasis from lung carcinoma. Our preliminary experience suggests that the presence of considerable overlap in the color Doppler patterns of mural blood flow in inflammatory and neoplastic lesions. Color Doppler sonography alone without spectral waveform analysis may not distinguish focal inflammatory from neoplastic disorders of the gastrointestinal tract reliably. However, this technique potentially may be useful in diagnosing small bowel ischemia when thickened segments of small bowel are identified with absent flow.

Abstract

Graded compression sonography has proven to be of significant clinical value in the assessment of patients with right lower quadrant pain and possible appendicitis [1-3]. Despite its proven utility, a number of imaging pitfalls must be kept in mind when sonograms of the right lower quadrant are interpreted. The purpose of this pictorial essay is to illustrate a number of important limitations and areas of interpretive difficulty in sonography for appendicitis.

Abstract

To evaluate the accuracy of computed tomographic (CT) angiography in the detection of renal artery stenosis (RAS).CT angiography was performed in 31 patients undergoing conventional renal arteriography. CT angiographic data were reconstructed with shaded surface display (SSD) and maximum-intensity projection (MIP). Stenosis was graded with a four-point scale (grades 0-3). The presence of mural calcification, poststenotic dilatation, and nephrographic abnormalities was also noted.CT angiography depicted all main (n = 62) and accessory (n = 11) renal arteries that were seen at conventional arteriography. MIP CT angiography was 92% sensitive and 83% specific for the detection of grade 2-3 stenoses (> or = 70% stenosis). SSD CT angiography was 59% sensitive and 82% specific for the detection of grade 2-3 stenoses. The accuracy of stenosis grading was 80% with MIP and 55% with SSD CT angiography. Poststenotic dilatation and the presence of an abnormal nephrogram were 85% and 98% specific, respectively.CT angiography shows promise in the diagnosis of RAS. The accuracy of CT angiography varies with the three-dimensional rendering technique employed.

Abstract

To compare superior mesenteric artery (SMA) blood flow in healthy volunteers and patients with stenoses in the fasting state and after food intake by using phase-contrast (PC) cine magnetic resonance (MR) imaging.Ten healthy subjects, four asymptomatic patients (three with 50% stenosis, one with 70% stenosis), and one symptomatic patient (with 80% stenosis) were studied. All subjects were studied after fasting at least 8 hours and 15, 30, and 45 minutes after ingesting a standard meal.In healthy volunteers, SMA blood flow at all postprandial intervals increased significantly compared with that obtained after fasting (P < or = .0005). The percentage change in SMA blood flow 30 minutes after food intake provided the best distinction between the healthy subjects, the asymptomatic patients, and the symptomatic patient.Cine PC MR imaging is an effective, noninvasive technique for measuring SMA blood flow.

Abstract

We compared the effectiveness of pulsed magnetization transfer contrast (MTC) magnetic resonance imaging (MRI) and spin-echo MRI in detecting tumor necrosis.Adenocarcinoma cells were transplanted in the livers of 12 syngenic BDIX rats. To induce various degrees of tumor necrosis, the rats were randomly assigned to the following groups: 1) control; 2) localized hyperthermia; 3) intralesional cisplatin; and 4) hyperthermia plus intralesional cisplatin. At day 7 after treatment, the rats were imaged using a 1.5-T imager with 1) multiplanar gradient-recalled echo sequence (MPGR) 500/8/20 degrees with and without magnetization transfer contrast (MTC); 2) spin-echo 2500/20,80, and 3) spin-echo 300/20 pulse sequences. The rats were then sacrificed and pathologic specimens were prepared using MR images as guidance. T2 and ratios of signal intensity after saturation to signal intensity before saturation (Ms/Mo ratios) of the necrotic and granulation tissues and viable tumors were determined in 10 rats.Compared with standard MPGR images, MPGR images with MTC provided better contrast between the pathologic tissues and normal liver. However, T2 values were more useful than Ms/Mo ratios in distinguishing necrotic areas from viable tumor. The T2 values of coagulative necrosis and granulation tissue were significantly different from that of viable tumor. No significant difference between the Ms/Mo ratios of the different pathologic tissues and normal liver was found.Pulsed magnetization transfer contrast MRI was inferior to spin-echo MRI in distinguishing necrotic from viable tumors in rat livers using the pulse sequences described, and none of the sequences studied was thought to be reliable enough for this purpose.

Abstract

We sought to apply a new technique of computed tomographic angiography (CTA) to the preoperative and postoperative assessment of the abdominal aorta and its branches.After a peripheral intravenous contrast injection, the patient is continuously advanced through a spiral CT scanner, while maintaining a 30-second breath-hold. Thirty-five patients with abdominal aortic, renal, and visceral arterial disease have undergone CTA.Diagnostic three-dimensional images were obtained in patients with aortic aneurysms (n = 9), aortic dissections (n = 4), and mesenteric artery stenoses (n = 4). The technique has also been used to assess vessels after operative reconstruction or endovascular intervention in 18 patients. These preliminary studies have correlated well with conventional arteriographic findings. In aneurysmal disease both the lumen and mural thrombus and associated renal artery stenoses are visualized. The true and false channels of aortic dissections and the perfusion source of the visceral vessels are clearly shown; patency of visceral and renal reconstruction or stent placement are confirmed. CTA is relatively noninvasive and can be completed in less time than conventional angiography with less radiation exposure.This initial experience suggests that CTA may be a valuable alternative to conventional arteriography in the evaluation of the aorta and its branches.

Abstract

The authors present sliding thin-slab maximum intensity projection (STS-MIP) as a technique for improved visualization of blood vessels and airways from rapidly acquired thin-section CT data. The STS-MIP reconstructions can be computed rapidly and without operator intervention directly from the transaxial sections. The resulting images retain the high contrast resolution of thin-section (1-3 mm) CT while providing vascular or airway visibility within a sequence of overlapping thin-slabs (3-10 mm). Examples are presented of pulmonary vessels and airways derived from spiral CT and of pulmonary vessels and coronary arteries derived from electron-beam CT.

Abstract

Fourteen adult patients with clinically suspected AAC and inconclusive initial sonograms underwent follow-up sonography within 24 hours. Eight patients had initial studies demonstrating a normal thickness of the gallbladder wall. Four of these patients demonstrated progressive thickening of the gallbladder wall on follow-up scans and were diagnosed as having AAC. In three of these patients AAC was proved at surgery, and the remaining patient improved clinically after percutaneous cholecystostomy. Four other patients with normal gallbladder wall thickness on both the initial and follow-up sonograms had benign clinical follow-up results without evidence of AAC. The remaining six patients had a thickened gallbladder on the initial sonogram. In one of these patients, the gallbladder wall thickening resolved on follow-up sonography. In the remaining five patients the gallbladder wall thickening did not change. Four of these patients had benign follow-up results but one patient was found to have AAC at surgery. Follow-up sonography may be helpful to confirm AAC if there is progressive edema of the gallbladder wall. A normal gallbladder wall on an initial study does not exclude early AAC. Thickening of the gallbladder wall on initial studies still remains a problem and other ancillary criteria must be used to establish the diagnosis of AAC.

Abstract

The purpose of this study was to optimize a new rapid-acquisition MR pulse sequence, called fast multiplanar spoiled gradient-recalled (FMPSPGR) imaging, for breath-hold imaging of the liver and to compare unenhanced and contrast-enhanced FMPSPGR with standard spin-echo imaging in detecting liver tumors.The pulse sequence was optimized at 1.5 T with a healthy volunteer. Various scanning parameters were evaluated, and liver-spleen signal difference/noise measurements were used to estimate lesion contrast-to-noise ratios. We examined 24 patients with hepatic masses using the optimized sequence with spin-echo T1-weighted and T2-weighted imaging as well as unenhanced and gadopentetate dimeglumine-enhanced FMPSPGR imaging. The contrast-to-noise ratio for the hepatic tumors was determined for each sequence. Three radiologists who did not know the biopsy or test results reviewed all images for lesion conspicuity, lesion tissue specificity, and overall image quality.A comparison of unenhanced FMPSPGR images with spin-echo T1-weighted images showed a 40% improvement in mean contrast-to-noise ratio and a 70% improvement in liver signal-to-noise ratio for the FMPSPGR images. A comparison of gadopentetate dimeglumine-enhanced FMPSPGR images with spin-echo T1- and T2-weighted images showed a superior contrast-to-noise ratio for the enhanced FMPSPGR images in 17 (68%) of 25 hepatic lesions, which included all hepatic cysts (n = 3) and all hepatomas (n = 6), and in six of 12 patients with other liver tumors. The results of contrast-to-noise ratio for four patients with hemangiomas were mixed. For the remaining eight lesions, the contrast-to-noise ratio for spin-echo T1- and T2-weighted images predominated in three and five cases, respectively. Contrast-enhanced FMPSPGR images revealed a 40% and 300% increase in contrast-to-noise ratio compared with T2- and T1-weighted images, respectively. All three radiologists preferred the contrast-enhanced FMPSPGR images for overall image quality. For lesion conspicuity and specificity, however, the three radiologists differed, with a preference for the FMPSPGR images in 52%, 80%, and 40% of cases for lesion conspicuity and in 68%, 40%, and 60% of cases for lesion specificity.FMPSPGR is a new, ultrafast MR sequence that provides T1-weighted images of the liver during suspended respiration. Contrast-to-noise ratio and liver signal-to-noise ratio are significantly improved over those on conventional spin-echo T1-weighted images. The combination of breath-hold FMPSPGR with gadopentetate dimeglumine is an excellent technique that can be used to rapidly evaluate the liver with superior overall image quality. Contrast-to-noise ratios are generally superior to T2-weighted spin-echo images, making this technique a useful adjunct to conventional spin-echo MR imaging.

Abstract

The high mortality and morbidity rates associated with traumatic rupture of the hollow viscera have been attributed to the clinical difficulty in establishing an early diagnosis. CT has been shown to be accurate for detecting bowel and mesenteric injuries caused by blunt trauma and may be useful in predicting the need for either surgical repair or conservative management. However, many major gastrointestinal injuries have subtle CT findings. In this pictorial essay, we illustrate the broad spectrum of gastrointestinal abnormalities that can be shown by CT in patients with blunt abdominal trauma.

Abstract

Spiral computed tomography (CT) is a new technology that couples continuous tube rotation with continuous table feed. This allows compilation of a data set that has continuous anatomic information without the establishment of arbitrary boundaries at section interfaces as in conventional CT. The unique method of data collection of the spiral scanner has been combined with a dynamic intravenous contrast material bolus to image abdominal vasculature, specifically, the aorta, renal arteries, and splanchnic circulation. Through various techniques of image processing, including surface renderings and maximum-intensity projections, it is possible to obtain excellent anatomic detail of the aorta and its major branches. The authors applied this technique in 15 patients and reliably saw third-order aortic branches as well as third-order splenic-portal venous anatomic detail with remarkable clarity. Pathologic conditions detected include stenotic renal arteries, abdominal aortic dissection, abdominal aortic aneurysm, and celiac bypass graft occlusion.

Abstract

Quantitative measurements of arterial and venous blood flow were obtained with phase-contrast cine magnetic resonance (MR) imaging and compared with such measurements obtained by means of implanted ultrasound (US) blood flow probes in anesthetized dogs. The US flowmeter was enabled during a portion of each MR imaging sequence to allow virtually simultaneous data acquisition with the two techniques. MR imaging data were gated by means of electrocardiography and divided into 16 phases per cardiac cycle. The rates of portal venous blood flow measured with MR imaging and averaged across the cardiac cycle (710 mL/min +/- 230 [standard deviation]) correlated well with those measured with the flowmeter and averaged in like fashion (751 mL/min +/- 238) (r = .995, slope = 1.053). The correspondence in arterial blood flow was almost as good. No statistically significant difference existed between the paired measurements of blood flow obtained with MR imaging and the implanted probe. It is concluded that, as a noninvasive means of accurate quantification of blood flow, phase-contrast MR imaging may be especially useful in deep blood vessels in humans.

Abstract

The purpose of this study was to determine the sensitivity and specificity of color flow Doppler sonography for the specific diagnosis of focal hepatic lesions.Color flow Doppler images of 118 focal hepatic lesions in 108 patients were analyzed prospectively. In most patients, liver disease was suspected or known to be present before the Doppler images were obtained. Experienced sonologists obtained and interpreted all sonograms. The lesions were classified, according to their color flow pattern, into two main categories: lesions with internal vascularity and lesions with no internal vascularity. The color flow Doppler pattern of each lesion was correlated with the diagnosis of the lesion on a lesion-by-lesion basis. One hundred two lesions were proved by biopsy and 16 lesions were confirmed by evaluation with other imaging techniques. Lesions included 29 hepatocellular carcinomas, 64 metastases, one cholangiocarcinoma, and 24 benign lesions. The sensitivity and specificity of vascularity as shown by color Doppler imaging in the diagnosis of hepatocellular carcinoma were determined.The majority of hepatocellular carcinoma lesions (76%) had internal vascularity. Most of the metastases (67%) and benign lesions (75%) had no internal vascularity. When the presence of internal vascularity was used as the discriminating criterion, the sensitivity of color flow Doppler findings for the diagnosis of hepatocellular carcinoma was 0.76. The specificity of internal vascularity for the diagnosis of hepatocellular carcinoma vs other focal lesions was 0.69; for hepatocellular carcinoma vs metastases it was 0.67.Although most hepatocellular carcinomas have internal vascularity on color flow Doppler images, a significant number of metastases also have internal vascularity. This overlap limits the usefulness of color flow Doppler imaging for distinguishing hepatocellular carcinoma from metastatic tumors.

Abstract

The authors describe a technique for obtaining angiographic images by means of spiral computed tomography (CT), preprocessing of reconstructed three-dimensional sections to suppress bone, and maximum intensity projection. The technique has some limitations, but preliminary results in 48 patients have shown excellent anatomic correlation with conventional angiography in studies of the abdomen, the circle of Willis in the brain, and the extracranial carotid arteries. With continued development and evaluation, CT angiography may prove useful as a screening tool or replacement for conventional angiography in some patients.

Abstract

Ultrasound (US) of the liver surface with a high-frequency, small-parts, short-focused probe has been proposed as a method of diagnosing cirrhosis. US of the liver was performed in 50 consecutive patients undergoing diagnostic liver biopsy to assess the clinical usefulness of this noninvasive procedure in diagnosing hepatic cirrhosis. Eight patients had histologically proved cirrhosis, and 42 had no histologic evidence of cirrhosis. Seven of the eight patients with cirrhosis had a normal liver surface at US, and five of the 42 patients without cirrhosis had an abnormal liver surface. US of the liver surface with this probe was not reliable in this heterogeneous patient population.

Abstract

Over a 3-year period nine patients (mean age of 43 years) with acute abdominal pain and unsuspected abdominal neoplasms were referred for graded compression sonography to rule out appendicitis. Six of the nine patients had right lower quadrant neoplasms involving the cecum, terminal ileum, iliacus muscle, or iliac lymph nodes. However, in three patients neoplasm was noted outside the right iliac fossa involving the liver, right kidney, and upper abdominal mesentery. This study underscores the fact that in patients without sonographic evidence of acute appendicitis, a survey of the upper abdomen and right flank should routinely be performed in addition to scanning the right iliac fossa and pelvis. In patients more than 50 years of age neoplasm must also be kept in mind in the differential diagnosis of appendicitis.

Abstract

Mucocele of the appendix, a cystic mass resulting from a dilated appendiceal lumen caused by abnormal accumulation of mucus, is a rare entity that often is not considered when problems of the right lower quadrant are assessed. Preoperative recognition of mucocele of the appendix is important because of the possibility of rupture at surgery with development of pseudomyxoma peritonei and to predict malignant transformation. The appearances of mucoceles of the appendix on sonography, CT, and barium studies are illustrated.

Abstract

Abdominal and gastrointestinal disease may result in clinically important complications in immunocompromised patients. The major types of disease are opportunistic infections and immunodeficiency-associated neoplasms. A multimodality approach is often essential in the diagnosis and staging of these lesions. A combination of bacteriologic culture, endoscopy, barium studies, and cross-sectional imaging of the abdomen with computed tomography and sonography is required to assess the extent of the disease accurately.

Abstract

Focal appendicitis at the tip of the appendix has not been emphasized in the sonographic literature. We present the sonographic findings in four patients with pathologically confirmed acute appendicitis confined to the appendiceal tip. In all four patients, the base of the appendix had a normal appearance with maximal outer diameters measuring 4 to 6 mm. However, the inflamed tip was focally enlarged, measuring greater than 7 mm. The importance of a careful survey of the entire length of the appendix is emphasized to avoid a false-negative examination.

Abstract

Efficacy and safety of coaxial transthoracic fine-needle biopsy were evaluated in 54 patients with a history of malignant lymphoma and new chest lesions. Twenty-one patients had recurrent lymphoma. Correct diagnosis was made in 17 of the 21 patients (81%) after one biopsy. The sensitivity increased to 95% with repeat needle biopsy in three patients. Immunophenotyping (determining phenotype by means of immunologic examination) was essential for a definitive diagnosis of lymphoma in three patients. Non-lymphomatous malignancies were correctly diagnosed in 14 patients. An infectious organism was identified in 11 of 19 patients (58%) with benign lesions. Pneumothorax occurred in eight patients (15%), necessitating placement of a chest tube in two (4%). Mild hemoptysis was observed in four patients (7%). The authors conclude that coaxial transthoracic fine-needle biopsy in patients with a history of lymphoma is safe and accurate. The use of large cutting needles or surgical biopsy can be restricted to patients with false-negative findings at percutaneous biopsy and to patients in whom histologic transformation of lymphoma is suspected.

Abstract

This article focuses on the clinical role of high resolution computed tomography (CT) in the initial diagnosis and management of hemodynamically stable patients with blunt hepatic trauma. The increased utilization and diagnostic confidence afforded by CT has dramatically changed the surgical approach and need for laparatomy. The most important development has been the growing realization by many trauma surgeons that nonoperative management is often successful in stable patients who have CT evidence of isolated blunt hepatic trauma.

Abstract

The presence of gas within the appendix on plain abdominal radiographs is nonspecific and may or may not be associated with acute appendicitis. This finding, however, has not previously been reported with graded compression sonography of the right lower quadrant. Gas within the appendix was identified in four of 154 patients with a visualized appendix. All four patients had surgically confirmed acute appendicitis. Diagnostic difficulties were encountered in three of these four patients. In two patients, the findings were misinterpreted as an extraluminal gas-forming periappendiceal abscess. In an additional patient, the gas-filled appendix was initially mistaken for a segment of normal terminal ileum. The gas-filled appendix is a potential pitfall in the sonographic diagnosis of acute appendicitis. However, if other diagnostic criteria are met, gas within the appendix should not preclude establishing a sonographic diagnosis of appendicitis.

Abstract

Endovaginal sonography is rapidly becoming the diagnostic procedure of choice when evaluating patients with early pregnancy and assessing uterine abnormalities. However, there has been relatively little discussion of endovaginal sonography in the evaluation of adnexal masses. Using endovaginal sonography we studied 50 patients with clinically suspected adnexal masses, in whom transabdominal sonography was either suboptimal or failed to adequately characterize the mass. The purpose of this pictorial essay is to depict the normal anatomy of the ovaries and adnexa and highlight the unique contribution of endovaginal sonography in diagnosing a variety of adnexal masses, including tubal and ovarian lesions.

Abstract

During a 31-month period, evidence of gonadal vein thrombosis (GVT) was demonstrated by computed tomography (CT) in seven patients who had a broad spectrum of acute gastrointestinal inflammatory lesions, including diverticulitis, ulcerative colitis, Crohn disease, appendicitis with abscess, and perforated appendix with pseudomembranous colitis. All patients had lower abdominal pain, tenderness, fever, and leukocytosis. CT demonstrated thrombus through the length of the gonadal vein in each patient; the entire lumen of the vein was filled. No symptoms relating to GVT were present. GVT may resolve with treatment of the underlying enteric disease alone, and anticoagulant therapy may not be necessary.

Abstract

Newer techniques and applications of cross-sectional imaging of the abdomen with CT, ultrasound, and MR imaging have facilitated the diagnosis of diseases primarily involving the peritoneal cavity. CT peritoneography may aid in diagnosing complications of peritoneal dialysis, and detecting internal hernias and small peritoneal implants. Uncommon abnormalities such as sclerosing encapsulating peritonitis, cystic mesothelioma, and peritonitis from rupture of a retroperitoneal teratoma may also be diagnosed with CT or ultrasonography.

Abstract

Contrast-enhanced dynamic CT was used prospectively to diagnose and locate the site of active arterial intraabdominal hemorrhage in 18 patients. Active arterial extravasation was confirmed by angiography in five patients and by immediate surgery in nine. Two patients not undergoing surgery or angiography required multiple blood transfusions to correct rapidly falling hematocrit due to a coagulopathy. One patient died of hypovolemic shock, and autopsy confirmed a large acute retroperitoneal hematoma. Another patient with a splenic laceration and massive hemoperitoneum on CT had no active bleeding at the time of surgery, which was delayed 1 hr from the time of the CT. All patients were clinically thought to be hemodynamically stable and had systolic blood pressures greater than 110 mm Hg at the time of CT. In seven patients, hypotension developed either during (two patients) or immediately after (five patients) CT scanning, necessitating either immediate surgery or angiographic embolization. Contrast-enhanced dynamic CT is valuable in the diagnosis and localization of active arterial intraabdominal hemorrhage. Identification of the anatomic site of this potentially life-threatening hemorrhage is critical in determining whether immediate laparotomy or angiographic embolization is the preferred method of treatment.

Abstract

The sonographic and computed tomographic (CT) findings were reviewed in 17 patients with acute acalculous cholecystitis (AAC) over a 6-year period from 1984 to 1989. Of the six patients in whom both ultrasound and CT were performed, CT revealed marked gallbladder (GB) wall abnormalities, including perforation, and pericholecystic fluid collections in five patients not demonstrated by sonography. Of the total group, five patients had GB wall thicknesses of less than or equal to 3 mm (normal) at pathologic examination, which demonstrated a spectrum of disease ranging from acute hemorrhagic/necrotizing, to gangrenous acalculous cholecystitis with perforation. Sonography was falsely negative or significantly underestimated the severity of AAC in seven of the 13 patients examined by sonography. CT because of its superior ability to assess pericholecystic inflammation may provide additional diagnostic information even after a thorough sonographic study in cases of AAC.

Abstract

The authors describe the use of duplex and/or color Doppler ultrasonography of the pelvis in three women to demonstrate the presence of venous malformations. One patient with a pulsatile vaginal mass was shown to have an arteriovenous malformation of the vaginal wall. The second patient was shown to have an unsuspected venous angioma in the endometrial cavity. The third patient was shown to have adnexal varices that closely mimicked hydrosalpinx. In the latter two cases, the duplex and color flow capabilities of an endovaginal probe were especially important.